Augusta Ada King

Augusta Ada King, Countess of Lovelace (10 December 1815 – 27 November 1852), born.

Augusta Ada Byron, was an English writer chiefly known for her work on Charles Babbage's early mechanical general-purpose computer, the analytical engine. Her notes on the engine include what is recognised as the first algorithm intended to be processed by a machine; as such she is sometimes portrayed in popular culture as the "World's First Computer Programmer".

She was the only legitimate child of the poet Lord Byron (with Anne Isabella Milbanke), but had no relationship with her father, who died when she was nine. As a young adult she took an interest in mathematics, and in particular Babbage's work on the analytical engine. Between 1842 and 1843 she translated an article by Italian mathematician Luigi Menabrea on the engine, which she supplemented with a set of notes of her own. These notes contain what is considered the first computer program—that is, an algorithm encoded for processing by a machine. Though Babbage's engine was not built until nearly 150 years later in 1989–91, Lovelace's notes are important in the early history of computers. She also foresaw the capability of computers to go beyond mere calculating or number-crunching while others, including Babbage himself, focused only on these capabilities.

ü  Biography

Ada Augusta Byron was born on December 10, 1815, she was the only child of the poet Lord Byron, 6th Lord Byron and his wife, Anne Isabella "Annabella" Milbanke, Baroness Wentworth. Byron, and many of those who knew Byron, expected that the baby would be "the glorious boy", and there was some disappointment at the contrary news. She was named after Byron's half-sister, Augusta Leigh, and was called "Ada" by Byron himself.

Portrait by Margaret Sarah Carpenter

On 16 January 1816, Annabella, at Byron's behest, left for her parents' home at Kirkby Mallorytaking one-month-old Lovelace with her. Although English law gave fathers full custody of their children in cases of separation, Byron made no attempt to claim his parental rights. On 21 April, Byron signed the Deed of Separation, although very reluctantly, and left England for good a few days later. Byron did not have a relationship with his daughter and he died in 1824 when she was nine; her mother was the only significant parental figure in her life. Her mother, Annabella, became Baroness Wentworth in her own right in 1856, being then the sole remaining representative of the Wentworth Viscounts.

Lovelace was often ill, dating from her early childhood. At the age of eight she experienced headaches that obscured her vision. In June 1829, she was paralysed after a bout of the measles. She was subjected to continuous bed rest for nearly a year, which may have extended her period of disability. By 1831 she was able to walk with crutches.

Throughout her illnesses, Lovelace continued her education. Her mother's obsession with rooting out any of the insanity of which she accused Lord Byron was one of the reasons that Lovelace was taught mathematics from an early age. Lovelace was privately schooled in mathematics and science by William Frend, William King and Mary Somerville. One of her later tutors was the noted mathematician and logician Augustus De Morgan. From 1832, when she was seventeen, her remarkable mathematical abilities began to emerge, and her interest in mathematics dominated her life even after her marriage. In a letter to Lovelace's mother, De Morgan suggested that Lovelace's skill in mathematics could lead her to become "an original mathematical investigator, perhaps of first-rate eminence".

Lovelace never met her younger half-sister, Allegra Byron, daughter of Lord Byron and Claire Clairmont, who died in 1822 at the age of five. She did, however, have some contact with Elizabeth Medora Leigh, the daughter of Byron's half-sister Augusta Leigh. Augusta Leigh purposely avoided Lovelace as much as possible when she was introduced at Court.

ü  Adult years

Lovelace knew Mary Somerville, noted researcher and scientific author of the 19th century, who introduced her to Charles Babbage on 5 June 1833. Other acquaintances were Sir David Brewster, Charles Wheatstone, Charles Dickens and Michael Faraday.

By 1834, Lovelace was a regular at Court and started attending various events. She danced often and was able to charm many people and was described by most people as being dainty. However, John Hobhouse, Lord Byron's friend, was the exception and he described her as "a large, coarse-skinned young woman but with something of my friend's features, particularly the mouth". This description followed their meeting on 24 February 1834 in which Lovelace made it clear to Hobhouse that she did not like him, probably due to the influence of her mother, which led her to dislike all of her father's friends. This first impression was not to last, and they later became friends.

On 8 July 1835 she married William King, 8th Baron King, later 1st Earl of Lovelace in 1838. Her full title for most of her married life was "The Right Honourable the Countess of Lovelace". Their residence was a large estate at Ockham Park, in Ockham, Surrey, along with another estate on Loch Torridon and a home in London. They had three children; Byron born 12 May 1836, Anne Isabella (called Annabella, later Lady Anne Blunt) born 22 September 1837 and Ralph Gordon born 2 July 1839. Immediately after the birth of Annabella, Lovelace experienced "a tedious and suffering illness, which took months to cure".

In 1841, Lovelace and Medora Leigh (daughter of Lord Byron's half-sister Augusta Leigh) were told by Lovelace's mother that Byron, her father, was also Medora's father. On 27 February 1841, Lovelace wrote to her mother: "I am not in the least astonished. In fact you merelyconfirm what I have for years and years felt scarcely a doubt about, but should have considered it most improper in me to hint to you that I in any way suspected". Lovelace did not blame the incestuous relationship on Byron, but instead blamed Augusta Leigh: "I fear she is more inherently wicked than he ever was". This did not prevent Lovelace's mother from attempting to destroy her daughter's image of her father, but instead drove her to attack Byron's image with greater intensity.

ü  Charles Babbage

Ada Lovelace met and corresponded with Charles Babbage on many occasions, including socially and in relation to Babbage's Difference Engine and Analytical Engine. Babbage was impressed by Lovelace's intellect and writing skills. He called her "The Enchantress of Numbers". In 1843 he wrote of her:

Forget this world and all its troubles and if possible its multitudinous Charlatans – every thing
in short but the Enchantress of Numbers.

During a nine-month period in 1842–43, Lovelace translated Italian mathematician Luigi Menabrea's memoir on Babbage's newest proposed machine, the Analytical Engine. With the article, she appended a set of notes. The notes are longer than the memoir itself and include (Section G), in complete detail, a method for calculating a sequence of Bernoulli numbers with the Engine, which would have run correctly had the Analytical Engine been built. Based on this work, Lovelace is now widely credited with being the first computer programmer and her method is recognised as the world's first computer program.

Some biographers debate the extent of her original contributions. Dorothy Stein, author of Ada: A Life and a Legacy, contends that the programs were mostly written by Babbage himself. Babbage wrote the following on the subject, in his Passages from the Life of a Philosopher (1864).

I then suggested that she add some notes to Menabrea's memoir, an idea which was immediately adopted. We discussed together the various illustrations that might be introduced: I suggested several but the selection was entirely her own. So also was the algebraic working out of the different problems, except, indeed, that relating to the numbers of Bernoulli, which I had offered to do to save Lady Lovelace the trouble. This she sent back to me for an amendment, having detected a grave mistake which I had made in the process.

The level of impact of Lovelace on Babbage's engines is difficult to resolve from Babbage's writings due to Babbage's tendency not to acknowledge  the influence of other people in his work

ü  Death

Lovelace died at the age of thirty-six, on 27 November 1852, from uterine cancer and bloodletting by her physicians. She was buried, at her request, next to her father at the Church of St. Mary Magdalene in Hucknall, Nottingham

Hypatia

Hypatia (AD 350–370, d. March 415)

was a Greek scholar from Alexandria, Egypt, who is considered the first notable woman mathematician; she also taught philosophy and astronomy. As a Neoplatonist philosopher, she belonged to the mathematic tradition of the Academy of Athens, as represented by Eudoxus of Cnidus; she was of the intellectual school of the 3rd century thinker Plotinus, which encouraged logic and mathematical study in place of empirical enquiry. Hypatia lived in Roman Egypt, and was assassinated by a Christian mob who accused her of causing religious turmoil. Kathleen Wilder proposes that the murder of Hypatia marked the end of Classical antiquity, while Maria Dzielska and Christian Wildberg note that Hellenistic philosophy continued to flourish in the 5th and 6th centuries, and perhaps until the age ofJustinian

ü Life

Hypatia

The mathematician and philosopher Hypatia of Alexandria was the daughter of the mathematicianTheon Alexandricus (ca. 335–405), who educated her as was the norm for boys; he was the last librarian of the Library of Alexandria in the Museum of Alexandria. She was educated at Athens and in Italy; at about AD 400, she became headmistress of the Platonist school at Alexandria, where she imparted the knowledge of Plato and Aristotle, to any student; the pupils included pagans, Christians, and foreigners. The contemporary, 5th-century sources do not identify Hypatia of Alexandria as practicant of any religion, but, two hundred years later, the 7th-century Egyptian Coptic bishop John of Nikiû identified her as a Hellenistic pagan and that "she was devoted at all times to magic, astrolabes and instruments of music, and she beguiled many people through her Satanic wiles". Nonetheless, despite the historical record, the Christians later used Hypatia as symbolic of feminine Virtue. Moreover, the Byzantine Suda encyclopaedia reported that Hypatia was "the wife of Isidore the Philosopher" (Isidore of Alexandria), and that they (husband and wife) had agreed she would remain a virgin; and that she rejected a suitor with her menstrual rags, saying that they demonstrated "nothing beautiful" about carnal desire.

Hypatia corresponded with former pupil Synesius of Cyrene, who became bishop of Ptolemais in AD 410; and an author of the Christian Holy Trinity doctrine derived from the Platonic education he received from her. Together with the references by the pagan philosopher Damascius, these are the extant records left by Hypatia's pupils at the Platonist school of Alexandria. The contemporary Christian historiographer Socrates Scholasticus described her in Ecclesiastical History:

“	There was a woman at Alexandria named Hypatia, daughter of the philosopher Theon, who made such attainments in literature and science, as to far surpass all the philosophers of her own time. Having succeeded to the school of Plato and Plotinus, she explained the principles of philosophy to her auditors, many of whom came from a distance to receive her instructions. On account of the self-possession and ease of manner which she had acquired in consequence of the cultivation of her mind, she not infrequently appeared in public in the presence of the magistrates. Neither did she feel abashed in going to an assembly of men. For all men on account of her extraordinary dignity and virtue admired her the more.	”

ü Death

Hypatia was believed to be the cause of strained relations between Orestes, the Imperial Roman Prefect, and the Patriarch Cyril, thus she attracted the hatred of the Christians of Alexandria, who wanted the politician and the priest to reconcile. One day, in March AD 415, during Lent, a Christian mob of Nitrian monks led by "Peter the Reader," waylaid Hypatia's chariot as she travelled home. The monks attacked Hypatia, then stripped her naked, to humiliate her, then dragged her through the streets to the recently Christianised Caesareum church, where they killed her. The reports suggest that the mob of Christian monks flayed her body with ostraca (pot shards), and then burned.

Galileo Galilei

    Galileo Galilei 15 February 1564 – 8 January 1642, commonly known as Galileo

Was an Italian physicist, mathematician,astronomer and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism. Galileo has been called the "father of modern observational astronomy", the "father of modern physics", the "father of science", and "the Father of Modern Science". Stephen Hawking says, "Galileo, perhaps more than any other single person, was responsible for the birth of modern science."

Galileo's championing of Copernicanism was controversial within his lifetime, when a large majority of philosophers and astronomers still subscribed to the geocentric view that the Earth is at the centre of the universe. After 1610, when he began publicly supporting the heliocentric view, which placed the Sun at the centre of the universe, he met with bitter opposition from some philosophers and clerics, and two of the latter eventually denounced him to the Roman Inquisition early in 1615. In February 1616, although he had been cleared of any offence, the Catholic Church nevertheless condemned heliocentrism as "false and contrary to Scripture", and Galileo was warned to abandon his support for it—which he promised to do. When he later defended his views in his most famous work, Dialogue Concerning the Two Chief World Systems, published in 1632, he was tried by the Inquisition, found "vehemently suspect of heresy", forced to recant, and spent the rest of his life under house arrest.

    Early life

Galileo was born in Pisa (then part of the Duchy of Florence), Italy, the first of six children of Vincenzo Galilei, a famous lutenist, composer, and music theorist, and Giulia Ammannati. Four of their six children survived infancy, and the youngest Michelangelo (or Michelagnolo) also became a noted lutenist and composer.

Galileo's full name was Galileo di Vincenzo Bonaiuti de' Galilei. At the age of 8, his family moved to Florence, but he was left with Jacopo Borghini for two years. He then was educated in the Camaldolese Monastery at Vallombrosa, 35 km southeast of Florence.

Although a genuinely pious Roman Catholic, Galileo fathered three children out of wedlock with Marina Gamba. They had two daughters, Virginia in 1600 and Livia in 1601, and one son, Vincenzo, in 1606. Because of their illegitimate birth, their father considered the girls unmarriageable. Their only worthy alternative was the religious life. Both girls were sent to the convent of San Matteo in Arcetri and remained there for the rest of their lives. Virginia took the name Maria Celeste upon entering the convent. She died on 2 April 1634, and is buried with Galileo at the Basilica of Santa Croce, Florence. Livia took the name Sister Arcangela and was ill for most of her life. Vincenzo was laterlegitimized and married Sestilia Bocchineri.

    Career as a scientist

Although he seriously considered the priesthood as a young man, he enrolled for a medical degree at the University of Pisa at his father's urging. He did not complete this degree, but instead studied mathematics.

Galileo was also studious of disegno, a term encompassing fine art, and in 1588 attained an instructor position in the Accademia delle Arti del Disegno in Florence, teaching perspective and chiaroscuro. Being inspired by the artistic tradition of the city and the works of the Renaissance artists, Galileo acquired an aesthetic mentality. While a young teacher at the Accademia, he began a life-long friendship with the Florentine painter Cigoli, who included Galileo's lunar observations in one of his paintings.

In 1589, he was appointed to the chair of mathematics in Pisa. In 1591 his father died and he was entrusted with the care of his younger brother Michelagnolo. In 1592, he moved to the University of Padua, teaching geometry, mechanics, and astronomy until 1610.

Cristiano Banti's 1857 painting Galileo facing the Roman Inquisition

    Death

Tomb of Galileo Galilei, Santa Croce

Galileo continued to receive visitors until 1642, when, after suffering fever and heart palpitations, he died on January 8, 1642, at age 77. The Grand Duke of Tuscany, Ferdinando II, wished to bury him in the main body of the Basilica of Santa Croce, next to the tombs of his father and other ancestors, and to erect a marble mausoleum in his honour. These plans were scrapped, however, after Pope Urban VIII and his nephew, Cardinal Francesco Barberini, protested, because Galileo was condemned by the Catholic Church for "vehement suspicion of heresy". He was instead buried in a small room next to the novices' chapel at the end of a corridor from the southern transept of the basilica to the sacristy. He was reburied in the main body of the basilica in 1737 after a monument had been erected there in his honour; during this move, three fingers and a tooth were removed from his remains. One of these fingers, the middle finger from Galileo's right hand, is currently on exhibition at the Museo Galileo in Florence, Italy.

    Scientific methods

Galileo made original contributions to the science of motion through an innovative combination of experiment and mathematics. More typical of science at the time were the qualitative studies of William Gilbert, on magnetism and electricity. Galileo's father, Vincenzo Galilei, alutenist and music theorist, had performed experiments establishing perhaps the oldest known non-linear relation in physics: for a stretched string, the pitch varies as the square root of the tension. These observations lay within the framework of the Pythagorean tradition of music, well-known to instrument makers, which included the fact that subdividing a string by a whole number produces a harmonious scale. Thus, a limited amount of mathematics had long related music and physical science, and young Galileo could see his own father's observations expand on that tradition.

Galileo is perhaps the first to clearly state that the laws of nature are mathematical. In The Assayer he wrote "Philosophy is written in this grand book, the universe ... It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures;...." His mathematical analyses are a further development of a tradition employed by late scholastic natural philosophers, which Galileo learned when he studied philosophy. Although he tried to remain loyal to the Catholic Church, his adherence to experimental results, and their most honest interpretation, led to a rejection of blind allegiance to authority, both philosophical and religious, in matters of science. In broader terms, this aided the separation of science from both philosophy and religion; a major development in human thought.

By the standards of his time, Galileo was often willing to change his views in accordance with observation. In order to perform his experiments, Galileo had to set up standards of length and time, so that measurements made on different days and in different laboratories could be compared in a reproducible fashion. This provided a reliable foundation on which to confirm mathematical laws using inductive reasoning.

Galileo showed a remarkably modern appreciation for the proper relationship between mathematics, theoretical physics, and experimental physics. He understood the parabola, both in terms of conic sections and in terms of the ordinate (y) varying as the square of the abscissa(x). Galilei further asserted that the parabola was the theoretically ideal trajectory of a uniformly accelerated projectile in the absence offriction and other disturbances. He conceded that there are limits to the validity of this theory, noting on theoretical grounds that a projectile trajectory of a size comparable to that of the Earth could not possibly be a parabola, but he nevertheless maintained that for distances up to the range of the artillery of his day, the deviation of a projectile's trajectory from a parabola would only be very slight.

    Astronomy

    Contributions

Fresco by Giuseppe Bertini depicting Galileo showing the Doge of Venice how to use the telescope

It was on this page that Galileo first noted an observation of the moons of Jupiter. This observation upset the notion that all celestial bodies must revolve around the Earth. Galileo published a full description inSidereus Nuncius in March 1610

Based only on uncertain descriptions of the first practical telescope, invented by Hans Lippersheyin the Netherlands in 1608, Galileo, in the following year, made a telescope with about 3x magnification. He later made improved versions with up to about 30x magnification. With aGalilean telescope the observer could see magnified, upright images on the earth – it was what is commonly known as a terrestrial telescope, or spyglass. He could also use it to observe the sky; for a time he was one of those who could construct telescopes good enough for that purpose. On 25 August 1609, he demonstrated his first telescope to Venetian lawmakers. His telescopes were also a profitable sideline for Galileo selling them to merchants who found them useful both at sea and as items of trade. He published his initial telescopic astronomical observations in March 1610 in a brief treatise entitled Sidereus Nuncius (Starry Messenger).

On 7 January 1610 Galileo observed with his telescope what he described at the time as "three fixed stars, totally invisible by their smallness", all close to Jupiter, and lying on a straight line through it. Observations on subsequent nights showed that the positions of these "stars" relative to Jupiter were changing in a way that would have been inexplicable if they had really been fixed stars. On 10 January Galileo noted that one of them had disappeared, an observation which he attributed to its being hidden behind Jupiter. Within a few days he concluded that they wereorbiting Jupiter: He had discovered three of Jupiter's four largest satellites (moons). He discovered the fourth on 13 January. These satellites are now called Io, Europa, Ganymede, and Callisto. Galileo named the group of four the Medicean stars, in honour of his future patron,Cosimo II de' Medici, Grand Duke of Tuscany, and Cosimo's three brothers. Later astronomers, however, renamed them Galilean satellites in honour of their discoverer.

Once Galileo realized what he had seen a few days later, his observations of the satellites of Jupiter created a revolution in astronomy that reverberates to this day: a planet with smaller planets orbiting it did not conform to the principles of Aristotelian Cosmology, which held that all heavenly bodies should circle the Earth, and many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing. His observations were confirmed by the observatory of Christopher Clavius and he received a hero's welcome when he visited Rome in 1611.

Galileo continued to observe the satellites over the next eighteen months, and by mid 1611 he had obtained remarkably accurate estimates for their periods—a feat which Kepler had believed impossible.

Galileo e Viviani, 1892, Tito Lessi

Statue outside the Uffizi, Florence

Leonardo di ser Piero da Vinci (April 15, 1452 – May 2, 1519) was an Italian

Renaissance polymath: painter, sculptor, architect, musician, scientist,mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer. Leonardo has often been described as the archetype of the Renaissance Man, a man of "unquenchable curiosity" and "feverishly inventive imagination". He is widely considered to be one of the greatest painters of all time and perhaps the most diversely talented person ever to have lived. According to art historian Helen Gardner, the scope and depth of his interests were without precedent and "his mind and personality seem to us superhuman, the man himself mysterious and remote". Marco Rosci points out, however, that while there is much speculation about Leonardo, his vision of the world is essentially logical rather than mysterious, and that the empirical methods he employed were unusual for his time.

Born out of wedlock to a notary, Piero da Vinci, and a peasant woman, Caterina, at Vinci in the region of Florence, Leonardo was educated in the studio of the renowned Florentine painter, Verrocchio. Much of his earlier working life was spent in the service of Ludovico il Moro in Milan. He later worked in Rome, Bologna and Venice and spent his last years in France, at the home awarded him by Francis I.

Leonardo was and is renowned primarily as a painter.

Leonardo is revered for his technological ingenuity. He conceptualised a helicopter, a tank, concentrated solar power, a calculator, the double hull and outlined a rudimentary theory ofplate tectonics. Relatively few of his designs were constructed or were even feasible during his lifetime, but some of his smaller inventions, such as an automated bobbin winder and a machine for testing the tensile strength of wire, entered the world of manufacturing unheralded. He made important discoveries in anatomy, civil engineering, optics, andhydrodynamics, but he did not publish his findings and they had no direct influence on later science.

·        Life

v Childhood, 1452–1466

Leonardo's childhood home in Anchiano

Leonardo was born on April 15, 1452, "at the third hour of the night" in the Tuscan hill town ofVinci, in the lower valley of the Arno River in the territory of Florence. He was the out-of-wedlockson of the wealthy Messer Piero Fruosino di Antonio da Vinci, a Florentine legal notary, and Caterina, a peasant. Leonardo had no surname in the modern sense, “da Vinci” simply meaning “of Vinci”: his full birth name was "Lionardo di ser Piero da Vinci", meaning "Leonardo, (son) of (Mes)ser Piero from Vinci". The inclusion of the title "ser" indicated that Leonardo's father was a gentleman.

Little is known about Leonardo's early life. He spent his first five years in the hamlet of Anchiano in the home of his mother, then from 1457 lived in the household of his father, grandparents and uncle, Francesco, in the small town of Vinci. His father had married a sixteen-year-old girl named Albiera, who loved Leonardo but died young. When Leonardo was sixteen his father married again, to twenty-year-old Francesca Lanfredini. It was not until his third and fourth marriages that Ser Piero produced legitimate heirs.

Leonardo received an informal education in Latin, geometry and mathematics. In later life, Leonardo only recorded two childhood incidents. One, which he regarded as an omen, was when akite dropped from the sky and hovered over his cradle, its tail feathers brushing his face. The second occurred while exploring in the mountains. He discovered a cave and was both terrified that some great monster might lurk there, and driven by curiosity to find out what was inside.

Leonardo's early life has been the subject of historical conjecture. Vasari, the 16th-century biographer of Renaissance painters tells of how a local peasant made himself a round shield and requested that Ser Piero have it painted for him. Leonardo responded with a painting of a monster spitting fire which was so terrifying that Ser Piero sold it to a Florentine art dealer, who sold it to the Duke of Milan. Meanwhile, having made a profit, Ser Piero bought a shield decorated with a heart pierced by an arrow, which he gave to the peasant.

v Verrocchio's workshop, 1466–1476

In 1466, at the age of fourteen, Leonardo was apprenticed to the artist Andrea di Cione, known asVerrocchio, whose workshop was "one of the finest in Florence". Other famous painters apprenticed or associated with the workshop include Domenico Ghirlandaio, Perugino, Botticelli, and Lorenzo di Credi. Leonardo would have been exposed to both theoretical training and a vast range of technical skills including drafting, chemistry, metallurgy, metal working, plaster casting, leather working, mechanics and carpentry as well as the artistic skills of drawing, painting, sculpting and modelling.

Much of the painted production of Verrocchio's workshop was done by his employees. According to Vasari, Leonardo collaborated with Verrocchio on his Baptism of Christ, painting the young angel holding Jesus' robe in a manner that was so far superior to his master's that Verrocchio put down his brush and never painted again. On close examination, the painting reveals much that has been painted or touched up over the tempera using the new technique of oil paint, with the landscape, the rocks that can be seen through the brown mountain stream and much of the figure of Jesus bearing witness to the hand of Leonardo. Leonardo himself may have been the model for two existent works by Verrocchio: the bronze statue of David in the Bargello, and the Archangel Raphael in Tobias and the Angel.

By 1472, at the age of twenty, Leonardo qualified as a master in the Guild of St Luke, the guild of artists and doctors of medicine, but even after his father set him up in his own workshop, his attachment to Verrocchio was such that he continued to collaborate with him. Leonardo's earliest known dated work is a drawing in pen and ink of the Arno valley, drawn on August 5, 1473.

v Professional life, 1476–1513

Florentine court records of 1476 show that Leonardo and three other young men were charged with sodomy, and acquitted. From that date until 1478 there is no record of his work or even of his whereabouts. In 1478 he left Verroccio's studio and was no longer resident at his father's house. One writer, the "Anonimo" Gaddiano claims that in 1480 he was living with the Medici and working in the Garden of the Piazza San Marco in Florence, aNeo-Platonic academy of artists, poets and philosophers that the Medici had established. In January 1478 he received his first independent commission, to paint an altarpiece in 1478 for the Chapel of St Bernard in the Palazzo Vecchio and The Adoration of the Magi in March 1481 for the Monks of San Donato a Scopeto. Neither important commission was completed, the second being interrupted when Leonardo went to Milan.

In 1482 Leonardo, who according to Vasari was a most talented musician, created a silverlyre in the shape of a horse's head. Lorenzo de' Medici sent Leonardo, bearing the lyre as a gift, to Milan, to secure peace with Ludovico il Moro, Duke of Milan. At this time Leonardo wrote an often-quoted letter to Ludovico, describing the many marvellous and diverse things that he could achieve in the field of engineering and informing the Lord that he could also paint.

Leonardo worked in Milan from 1482 until 1499. He was commissioned to paint the Virgin of the Rocks for the Confraternity of the Immaculate Conception, and The Last Supper for the monastery of Santa Maria delle Grazie. Between 1493 and 1495 Leonardo listed a woman called Caterina among his dependents in his taxation documents. When she died in 1495, the list of funeral expenditures suggests that she was his mother.

Leonardo was employed on many different projects for Ludovico, including the preparation of floats and pageants for special occasions, designs for a dome for Milan Cathedral and a model for a huge equestrian monument to Francesco Sforza, Ludovico's predecessor. Seventy tons of bronze were set aside for casting it. The monument remained unfinished for several years, which was not unusual for Leonardo. In 1492 the clay model of the horse was completed. It surpassed in size the only two large equestrian statues of the Renaissance, Donatello's statue of Gattemelata in Padua and Verrocchio's Bartolomeo Colleoni in Venice, and became known as the "Gran Cavallo".

Study of horse from Leonardo's journals

Leonardo began making detailed plans for its casting, however, Michelangelo rudely implied that Leonardo was unable to cast it. In November 1494 Ludovico gave the bronze to be used for cannons to defend the city from invasion by Charles VIII.

At the start of the Second Italian War in 1499, the invading French troops used the life-size clay model for the "Gran Cavallo" for target practice. With Ludovico Sforza overthrown, Leonardo, with his assistant Salai and friend, the mathematician Luca Pacioli, fled Milan for Venice, where he was employed as a military architect and engineer, devising methods to defend the city from naval attack. On his return to Florence in 1500, he and his household were guests of the Servite monks at the monastery of Santissima Annunziata and were provided with a workshop where, according to Vasari, Leonardo created the cartoon ofThe Virgin and Child with St. Anne and St. John the Baptist, a work that won such admiration that "men and women, young and old" flocked to see it "as if they were attending a great festival".

In Cesena, in 1502 Leonardo entered the service of Cesare Borgia, the son of Pope Alexander VI, acting as a military architect and engineer and travelling throughout Italy with his patron. Leonardo created a mapof Cesare Borgia's stronghold, a town plan of Imola in order to win his patronage. Maps were extremely rare at the time and it would have seemed like a new concept; upon seeing it, Cesare hired Leonardo as his chief military engineer and architect. Later in the year, Leonardo produced another map for his patron, one of Chiana Valley, Tuscany so as to give his patron a better overlay of the land and greater strategic position. He created this map in conjunction with his other project of constructing a dam from the sea to Florence in order to allow a supply of water to sustain the canalduring all seasons.

Leonardo returned to Florence where he rejoined the Guild of St Luke on October 18, 1503, and spent two years designing and painting a great mural of The Battle of Anghiari for the Signoria, with Michelangelo designing its companion piece, The Battle of Cascina. In Florence in 1504, he was part of a committee formed to relocate, against the artist's will, Michelangelo's statue of David.

In 1506 Leonardo returned to Milan. Many of his most prominent pupils or followers in painting either knew or worked with him in Milan, including Bernardino Luini, Giovanni Antonio Boltraffioand Marco D'Oggione. However, he did not stay in Milan for long because his father had died in 1504, and in 1507 he was back in Florence trying to sort out problems with his brothers over his father's estate. By 1508 Leonardo was back in Milan, living in his own house in Porta Orientale in the parish of Santa Babila.

v Old age, 1513–1519

From September 1513 to 1516, Leonardo spent much of his time living in the Belvedere in the Vatican in Rome, where Raphael andMichelangelo were both active at the time. In October 1515, Francis I of France recaptured Milan. On December 19, Leonardo was present at the meeting of Francis I and Pope Leo X, which took place in Bologna. Leonardo was commissioned to make for Francis a mechanical lion which could walk forward, then open its chest to reveal a cluster of lilies. In 1516, he entered François' service, being given the use of the manor house Clos Lucé near the king's residence at the royal Château d'Amboise. It was here that he spent the last three years of his life, accompanied by his friend and apprentice, Count Francesco Melzi, and supported by a pension totalling 10,000 scudi.

Leonardo died at Clos Lucé, on May 2, 1519. Francis I had become a close friend. Vasari records that the King held Leonardo's head in his arms as he died, although this story, beloved by the French and portrayed in romantic paintings by Ingres, Ménageot and other French artists, as well as by Angelica Kauffmann, may be legend rather than fact. Vasari also tells us that in his last days, Leonardo sent for a priest to make his confession and to receive the Holy Sacrament. In accordance to his will, sixty beggars followed his casket. He was buried in the Chapel of Saint-Hubert in Château d'Amboise. Melzi was the principal heir and executor, receiving as well as money, Leonardo's paintings, tools, library and personal effects. Leonardo also remembered his other long-time pupil and companion, Salai and his servant Battista di Vilussis, who each received half of Leonardo's vineyards, his brothers who received land, and his serving woman who received a black cloak "of good stuff" with a fur edge.

v Florence — Leonardo's artistic and social background

Florence, at the time of Leonardo's youth, was the centre of Christian Humanist thought and culture. Leonardo commenced his apprenticeship with Verrocchio in 1466, the year that Verrocchio's master, the great sculptor Donatello, died. The painter Uccello whose early experiments with perspective were to influence the development of landscape painting, was a very old man. The painters Piero della Francescaand Fra Filippo Lippi, sculptor Luca della Robbia, and architect and writer Leon Battista Alberti were in their sixties. The successful artists of the next generation were Leonardo's teacher Verrocchio, Antonio Pollaiuolo and the portrait sculptor, Mino da Fiesole whose lifelike busts give the most reliable likenesses of Lorenzo Medici's father Piero and uncle Giovanni.

Leonardo's youth was spent in a Florence that was ornamented by the works of these artists and by Donatello's contemporaries, Masaccio whose figurative frescoes were imbued with realism and emotion andGhiberti whose Gates of Paradise, gleaming with gold leaf, displayed the art of combining complex figure compositions with detailed architectural backgrounds. Piero della Francesca had made a detailed study of perspective, and was the first painter to make a scientific study of light. These studies and Alberti'sTreatise were to have a profound effect on younger artists and in particular on Leonardo's own observations and artworks.

A prevalent tradition in Florence was the small altarpiece of the Virgin and Child. Many of these were created in tempera or glazed terracotta by the workshops of Filippo Lippi, Verrocchio and the prolific della Robbia family. Leonardo's early Madonnas such as The Madonna with a carnation and The Benois Madonna followed this tradition while showing idiosyncratic departures, particularly in the case of the Benois Madonna in which the Virgin is set at an oblique angle to the picture space with the Christ Child at the opposite angle. This compositional theme was to emerge in Leonardo's later paintings such as TheVirgin and Child with St. Anne.

Leonardo was a contemporary of Botticelli, Domenico Ghirlandaio and Perugino, who were all slightly older than he was. He would have met them at the workshop of Verrocchio, with whom they had associations, and at the Academy of the Medici. Botticelli was a particular favourite of the Medici family and thus his success as a painter was assured. Ghirlandaio and Perugino were both prolific and ran large workshops. They competently delivered commissions to well-satisfied patrons who appreciated Ghirlandaio's ability to portray the wealthy citizens of Florence within large religious frescoes, and Perugino's ability to deliver a multitude of saints and angels of unfailing sweetness and innocence.

These three were among those commissioned to paint the walls of the Sistine Chapel, the work commencing with Perugino's employment in 1479. Leonardo was not part of this prestigious commission. His first significant commission, The Adoration of the Magi for the Monks of Scopeto, was never completed.

In 1476, during the time of Leonardo's association with Verrocchio's workshop, the Portinari Altarpiece by Hugo van der Goes arrived in Florence, bringing new painterly techniques from Northern Europe which were to profoundly effect Leonardo, Ghirlandaio, Perugino and others. In 1479, the Sicilian painter Antonello da Messina, who worked exclusively in oils, traveled north on his way to Venice, where the leading painter, Giovanni Bellini adopted the technique of oil painting, quickly making it the preferred method in Venice. Leonardo was also later to visit Venice.

Like the two contemporary architects, Bramante and Antonio da Sangallo the Elder, Leonardo experimented with designs for centrally planned churches, a number of which appear in his journals, as both plans and views, although none was ever realised.

Leonardo's political contemporaries were Lorenzo Medici (il Magnifico), who was three years older, and his popular younger brother Giuliano who was slain in the Pazzi Conspiracy in 1478. Ludovico il Moro who ruled Milan between 1479–1499 and to whom Leonardo was sent as ambassador from the Medici court, was also of Leonardo's age.

With Alberti, Leonardo visited the home of the Medici and through them came to know the older Humanist philosophers of whom Marsiglio Ficino, proponent of Neo Platonism, Cristoforo Landino, writer of commentaries on Classical writings, and John Argyropoulos, teacher of Greek and translator of Aristotlewere foremost. Also associated with the Academy of the Medici was Leonardo's contemporary, the brilliant young poet and philosopher Pico della Mirandola. Leonardo later wrote in the margin of a journal "The Medici made me and the Medici destroyed me." While it was through the action of Lorenzo that Leonardo was to receive his important Milanese commissions, it is not known exactly what Leonardo meant by this cryptic comment.

Although usually named together as the three giants of the High Renaissance, Leonardo, Michelangelo andRaphael were not of the same generation. Leonardo was twenty-three when Michelangelo was born and thirty-one when Raphael was born. Raphael only lived until the age of 37 and died in 1520, the year after Leonardo, but Michelangelo went on creating for another 45 years.

v Personal life

Within Leonardo's lifetime, his extraordinary powers of invention, his "outstanding physical beauty", "infinite grace", "great strength and generosity", "regal spirit and tremendous breadth of mind" as described by Vasari, as well as all other aspects of his life, attracted the curiosity of others. One such aspect is his respect for life evidenced by his vegetarianism and his habit, described by Vasari, of purchasing caged birds and releasing them.

Leonardo had many friends who are now renowned either in their fields or for their historical significance. They included the mathematician Luca Pacioli, with whom he collaborated on a book in the 1490s, as well as Franchinus Gaffurius and Isabella d'Este. Leonardo appears to have had no close relationships with women except for his friendship with the two Este sisters, Beatrice and Isabella. He drew a portrait of her while on a journey which took him through Mantua, and which appears to have been used to create a painted portrait now lost.

v Assistants and pupils

Gian Giacomo Caprotti da Oreno, nicknamed Salai or Il Salaino ("The Little Unclean One" i.e., the devil), entered Leonardo's household in 1490. After only a year, Leonardo made a list of his misdemeanours, calling him "a thief, a liar, stubborn, and a glutton", after he had made off with money and valuables on at least five occasions, and spent a fortune on clothes. Nevertheless, Leonardo treated him with great indulgence and he remained in Leonardo's household for the next thirty years. Salai executed a number of paintings under the name of Andrea Salai, but although Vasari claims that Leonardo "taught him a great deal about painting", his work is generally considered to be of less artistic merit than others among Leonardo's pupils, such as Marco d'Oggione and Boltraffio. In 1515, he painted a nude version of the Mona Lisa, known as Monna Vanna. Salai owned the Mona Lisa at the time of his death in 1525, and in his will it was assessed at 505 lire, an exceptionally high valuation for a small panel portrait.

In 1506, Leonardo took on another pupil, Count Francesco Melzi, the son of a Lombard aristocrat, who is considered to have been his favourite student. He travelled to France with Leonardo, and remained with him until the latter's death. Upon Leonardo's death, Melzi inherited the artistic and scientific works, manuscripts, and collections of Leonardo, and faithfully administered the estate.

v Painting

Despite the recent awareness and admiration of Leonardo as a scientist and inventor, for the better part of four hundred years his enormous fame rested on his achievements as a painter and on a handful of works, either authenticated or attributed to him that have been regarded as among the supreme masterpieces ever created.

These paintings are famous for a variety of qualities which have been much imitated by students and discussed at great length by connoisseurs and critics. Among the qualities that make Leonardo's work unique are the innovative techniques that he used in laying on the paint, his detailed knowledge of anatomy, light, botany and geology, his interest in physiognomy and the way in which humans register emotion in expression and gesture, his innovative use of the human form in figurative composition and his use of the subtle gradation of tone. All these qualities come together in his most famous painted works, the Mona Lisa, the Last Supper and the Virgin of the Rocks.

v Early works

Leonardo's early works begin with the Baptism of Christ painted in conjunction with Verrocchio. Two other paintings appear to date from his time at the workshop, both of which are Annunciations. One is small,59 centimetres (23 in) long and 14 centimetres (5.5 in) high. It is a "predella" to go at the base of a larger composition, in this case a painting by Lorenzo di Credi from which it has become separated. The other is a much larger work, 217 centimetres (85 in) long. In both these Annunciations, Leonardo has used a formal arrangement, such as in Fra Angelico's two well known pictures of the same subject, of the Virgin Mary sitting or kneeling to the right of the picture, approached from the left by an angel in profile, with rich flowing garment, raised wings and bearing a lily. Although previously attributed to Ghirlandaio, the larger work is now almost universally attributed to Leonardo.

v Paintings of the 1480s

Virgin of the Rocks, Louvre, possibly 1505–1508.

In the 1480s Leonardo received two very important commissions, and commenced another work which was also of ground-breaking importance in terms of composition. Unfortunately, two of the three were never finished, and the third took so long that it was subject to lengthy negotiations over completion and payment. One of these paintings is that of St. Jerome in the Wilderness. Bortolon associates this picture with a difficult period of Leonardo's life, and the signs of melancholy in his diary: "I thought I was learning to live; I was only learning to die."

Although the painting is barely begun the composition can be seen and it is very unusual. Jerome, as a penitent, occupies the middle of the picture, set on a slight diagonal and viewed somewhat from above. His kneeling form takes on a trapezoid shape, with one arm stretched to the outer edge of the painting and his gaze looking in the opposite direction. J. Wasserman points out the link between this painting and Leonardo's anatomical studies. Across the foreground sprawls his symbol, a great lion whose body and tail make a double spiral across the base of the picture space. The other remarkable feature is the sketchy landscape of craggy rocks against which the figure is silhouetted.

The daring display of figure composition, the landscape elements and personal drama also appear in the great unfinished masterpiece, the Adoration of the Magi, a commission from the Monks of San Donato a Scopeto. It is a very complex composition, of about 250 x 250 centimetres. Leonardo did numerous drawings and preparatory studies, including a detailed one in linear perspective of the ruined classical architecture which makes part of the backdrop to the scene. But in 1482 Leonardo went off to Milan at the behest of Lorenzo de' Medici in order to win favour with Ludovico il Moro and the painting was abandoned.

The third important work of this period is the Virgin of the Rocks which was commissioned in Milan for the Confraternity of the Immaculate Conception. The painting, to be done with the assistance of the de Predis brothers, was to fill a large complex altarpiece, already constructed. Leonardo chose to paint an apocryphal moment of the infancy of Christ when the Infant John the Baptist, in protection of an angel, met the Holy Family on the road to Egypt. In this scene, as painted by Leonardo, John recognizes and worships Jesus as the Christ. The painting demonstrates an eerie beauty as the graceful figures kneel in adoration around the infant Christ in a wild landscape of tumbling rock and whirling water. While the painting is quite large, about 200 × 120 centimetres, it is not nearly as complex as the painting ordered by the monks of St Donato, having only four figures rather than about fifty and a rocky landscape rather than architectural details. The painting was eventually finished; in fact, two versions of the painting were finished, one which remained at the chapel of the Confraternity and the other which Leonardo carried away to France. But the Brothers did not get their painting, or the de Predis their payment, until the next century.

The Last Supper (1498)

v Paintings of the 1490s

Leonardo's most famous painting of the 1490s is The Last Supper, also painted in Milan. The painting represents the last meal shared by Jesus with his disciples before his capture and death. It shows specifically the moment when Jesus has said "one of you will betray me". Leonardo tells the story of the consternation that this statement caused to the twelve followers of Jesus.

The novelist Matteo Bandello observed Leonardo at work and wrote that some days he would paint from dawn till dusk without stopping to eat, and then not paint for three or four days at a time. This, according to Vasari, was beyond the comprehension of the prior, who hounded him until Leonardo asked Ludovico to intervene. Vasari describes how Leonardo, troubled over his ability to adequately depict the faces of Christ and the traitor Judas, told the Duke that he might be obliged to use the prior as his model.

When finished, the painting was acclaimed as a masterpiece of design and characterisation, but it deteriorated rapidly, so that within a hundred years it was described by one viewer as "completely ruined". Leonardo, instead of using the reliable technique of fresco, had used tempera over a ground that was mainly gesso, resulting in a surface which was subject to mold and to flaking. Despite this, the painting has remained one of the most reproduced works of art, countless copies being made in every medium from carpets to cameos.

v Paintings of the 1500s

Mona Lisa or La Gioconda (1503–1505/1507)

Among the works created by Leonardo in the 16th century is the small portrait known as the Mona Lisa or "la Gioconda", the laughing one. In the present era it is arguably the most famous painting in the world. Its fame rests, in particular, on the elusive smile on the woman's face, its mysterious quality brought about perhaps by the fact that the artist has subtly shadowed the corners of the mouth and eyes so that the exact nature of the smile cannot be determined. The shadowy quality for which the work is renowned came to be called "sfumato" or Leonardo's smoke. Vasari, who is generally thought to have known the painting only by repute, said that "the smile was so pleasing that it seemed divine rather than human; and those who saw it were amazed to find that it was as alive as the original".

Other characteristics found in this work are the unadorned dress, in which the eyes and hands have no competition from other details, the dramatic landscape background in which the world seems to be in a state of flux, the subdued colouring and the extremely smooth nature of the painterly technique, employing oils, but laid on much like tempera and blended on the surface so that the brushstrokes are indistinguishable. Vasari expressed the opinion that the manner of painting would make even "the most confident master ... despair and lose heart." The perfect state of preservation and the fact that there is no sign of repair or overpainting is extremely rare in a panel painting of this date.

In the Virgin and Child with St. Anne (see below [StAnne]) the composition again picks up the theme of figures in a landscape which Wasserman describes as "breathtakingly beautiful" and harks back to the St Jerome picture with the figure set at an oblique angle. What makes this painting unusual is that there are two obliquely set figures superimposed. Mary is seated on the knee of her mother, St Anne. She leans forward to restrain the Christ Child as he plays roughly with a lamb, the sign of his own impending sacrifice.

This painting, which was copied many times, was to influence Michelangelo, Raphael, and Andrea del Sarto, and through them Pontormo and Correggio. The trends in composition were adopted in particular by the Venetian painters Tintoretto and Veronese.

v Drawings

Leonardo was not a prolific painter, but he was a most prolific draftsman, keeping journals full of small sketches and detailed drawings recording all manner of things that took his attention. As well as the journals there exist many studies for paintings, some of which can be identified as preparatory to particular works such as The Adoration of the Magi, The Virgin of the Rocks andThe Last Supper. His earliest dated drawing is a Landscape of the Arno Valley, 1473, which shows the river, the mountains, Montelupo Castle and the farmlands beyond it in great detail.

Among his famous drawings are the Vitruvian Man, a study of the proportions of the human body, the Head of an Angel, for The Virgin of the Rocks in the Louvre, a botanical study of Star of Bethlehem and a large drawing (160×100 cm) in black chalk on coloured paper of The Virgin and Child with St. Anne and St. John the Baptist in the National Gallery, London. This drawing employs the subtle sfumato technique of shading, in the manner of the Mona Lisa. It is thought that Leonardo never made a painting from it, the closest similarity being to The Virgin and Child with St. Anne in the Louvre.

·        Leonardo as observer, scientist and inventor

v Journals

Renaissance humanism saw no mutually exclusive polarities between the sciences and the arts, and Leonardo's studies in science and engineering are as impressive and innovative as his artistic work. These studies were recorded in notebooks comprising some 13,000 pages of notes and drawings, which fuse art and natural philosophy (the forerunner of modern science), made and maintained daily throughout Leonardo's life and travels, as he made continual observations of the world around him.

v Scientific studies

Leonardo's approach to science was an observational one: he tried to understand a phenomenon by describing and depicting it in utmost detail, and did not emphasize experiments or theoretical explanation. Since he lacked formal education in Latin and mathematics, contemporary scholars mostly ignored Leonardo the scientist, although he did teach himself Latin. In the 1490s he studied mathematics underLuca Pacioli and prepared a series of drawings of regular solids in a skeletal form to be engraved as plates for Pacioli's book De Divina Proportione, published in 1509.

v Anatomy

Leonardo's formal training in the anatomy of the human body began with his apprenticeship toAndrea del Verrocchio, his teacher insisting that all his pupils learn anatomy. As an artist, he quickly became master of topographic anatomy, drawing many studies of muscles, tendons and other visible anatomical features.

v Engineering and inventions

A design for a flying machine, (c. 1488)

During his lifetime Leonardo was valued as an engineer. In a letter to Ludovico il Moro he claimed to be able to create all sorts of machines both for the protection of a city and for siege. When he fled to Venice in 1499 he found employment as an engineer and devised a system of moveable barricades to protect the city from attack. He also had a scheme for diverting the flow of the Arno River, a project on which Niccolò Machiavelli also worked. Leonardo's journals include a vast number of inventions, both practical and impractical. They include musical instruments, hydraulic pumps, reversible crank mechanisms, finned mortar shells, and a steam cannon.

In 1502, Leonardo produced a drawing of a single span 720-foot (220 m) bridge as part of a civil engineering project for Ottoman Sultan Beyazid II of Istanbul. The bridge was intended to span an inlet at the mouth of the Bosporus known as the Golden Horn. Beyazid did not pursue the project, because he believed that such a construction was impossible. Leonardo's vision was resurrected in 2001 when a smaller bridge based on his design was constructed in Norway. On May 17, 2006, the Turkish government decided to construct Leonardo's bridge to span the Golden Horn.

For much of his life, Leonardo was fascinated by the phenomenon of flight, producing many studies of the flight of birds, including his c. 1505 Codex on the Flight of Birds, as well as plans for several flying machines, including a lighthang glider and a machine resembling a helicopter. The British television station Channel Four commissioned a documentary Leonardo's Dream Machines, for broadcast in 2003. Leonardo's machines were built and tested according to his original designs. Some of those designs proved a success, whilst others fared less well when practically tested.

·        Leonardo the legend

Within Leonardo's own lifetime his fame was such that the King of France carried him away like a trophy, and was claimed to have supported him in his old age and held him in his arms as he died. The interest in Leonardo has never slackened. The crowds still queue to see his most famous artworks, T-shirts bear his most famous drawing and writers, like Vasari, continue to marvel at his genius and speculate about his private life and, particularly, about what one so intelligent actually believed in.

Statue of Leonardo da Vinci at the Uffizi, Florence

The continued admiration that Leonardo commanded from painters, critics and historians is reflected in many other written tributes. Baldassare Castiglione, author of Il Cortegiano ("The Courtier"), wrote in 1528: "... Another of the greatest painters in this world looks down on this art in which he is unequalled ..." while the biographer known as "Anonimo Gaddiano" wrote, c. 1540: "His genius was so rare and universal that it can be said that nature worked a miracle on his behalf ...".

The 19th century brought a particular admiration for Leonardo's genius, causing Henry Fuseli to write in 1801: "Such was the dawn of modern art, when Leonardo da Vinci broke forth with a splendour that distanced former excellence: made up of all the elements that constitute the essence of genius ..." This is echoed by A. E. Rio who wrote in 1861: "He towered above all other artists through the strength and the nobility of his talents."

By the 19th century, the scope of Leonardo's notebooks was known, as well as his paintings. Hippolyte Taine wrote in 1866: "There may not be in the world an example of another genius so universal, so incapable of fulfilment, so full of yearning for the infinite, so naturally refined, so far ahead of his own century and the following centuries."

The famous art historian Bernard Berenson wrote in 1896: "Leonardo is the one artist of whom it may be said with perfect literalness: Nothing that he touched but turned into a thing of eternal beauty. Whether it be the cross section of a skull, the structure of a weed, or a study of muscles, he, with his feeling for line and for light and shade, forever transmuted it into life-communicating values."

The interest in Leonardo's genius has continued unabated; experts study and translate his writings, analyse his paintings using scientific techniques, argue over attributions and search for works which have been recorded but never found. Liana Bortolon, writing in 1967, said: "Because of the multiplicity of interests that spurred him to pursue every field of knowledge ... Leonardo can be considered, quite rightly, to have been the universal genius par excellence, and with all the disquieting overtones inherent in that term. Man is as uncomfortable today, faced with a genius, as he was in the 16th century. Five centuries have passed, yet we still view Leonardo with awe.