In about 1472, when he was twenty, Leonardo joined the Guild of St Luke, an organisation of artists and doctors of medicine. Even after his father set him up in his own workshop, Leonardo still enjoyed working at Verrocchio's workshop. Leonardo's earliest known work is a drawing in pen and ink of the Arno River valley. It has the date 5 August 1473. It is now in the Uffizi Gallery.
When Vasari writes about Leonardo, he uses words like "noble", "generous", "graceful" and "beautiful". Vasari tells us that as an adult Leonardo was a tall handsome man. He was so strong that he could bend horseshoes with his bare hands. His voice was so beautiful that it charmed everyone that heard it. Almost everyone wanted to be his friend. He loved animals, was a vegetarian and would buy birds at the market and set them free.
Very little is known about Leonardo's life and work between 1472 and 1481. He was probably busy in Florence. In 1478, he had an important commission to paint an altarpiece for the Monks of San Donato a Scopeto. The painting was to be the "Adoration of the Magi" ("The Three Wise Men"). The painting was never finished because Leonardo was sent away to Milan.
Leonardo was a very talented musician. In 1482, he made a silver lyre (a musical instrument) in the shape of a horse's head. At that time there was a new ruler in the city of Milan, in the north of Italy. Duke Ludovico il Moro was making other rulers nervous. Lorenzo Medici sent Leonardo to Milan as an ambassador. Lorenzo de' Medici wanted Leonardo to give Ludovico the lyre as a present from him. Leonardo wrote a letter to the Duke of Milan, telling him about all the clever and useful things that he could do, like making war machines. He wrote in the letter that he could "also paint". Leonardo did not know at the time that it was for painting that he would be mostly remembered. Leonardo stayed in Milan and worked for the Duke between 1482 and 1499. Part of his work was to design festivals and carnival processions. In Leonardo's note books are drawings of theatre costumes, amazing helmets and scenes that might be for the theatre.
Leonardo, like most other well-known artists of his time, had servants, young students and older assistants in his workshop. One of his young students was a boy whose name was Gian Giacomo Caprotti da Oreno. He was a handsome boy with beautiful long golden curls. He looked perfect as an artist's model for an angel. But he was such a difficult and dishonest boy that Leonardo called him "Salai" or "Salaino" which means "the little devil". Leonardo wrote in his notebook that Salai was very greedy, that he was a liar and that he had stolen things from the house at least five times. Salai stayed in Leonardo's household for thirty years as a pupil and a servant.
Leonardo's most important work for Duke Ludovico was to make a huge statue of the previous ruler, Francesco Sforza, on horseback. He started with the horse. After studying horses and drawing designs, he made a huge horse of clay. It was called the "Gran Cavallo". It was going to be cast in bronze. It was going to be the biggest bronze horse that had been made for more than a thousand years. Unfortunately, the bronze horse was never made. In 1494, Ludovico gave the bronze to be made into cannons because the French army was invading Milan. The huge clay horse was still standing when the French army invaded again in 1499. This time it was used for target practice and was completely destroyed.
While Leonardo was working for Duke Ludovico, he had two important painting commissions. One was to do an oil painting to go in a big altarpiece for the Confraternity of the Immaculate Conception. Leonardo did the painting twice. He left one with the monks in Milan, and took the other painting to France where it is now in the Louvre Museum. The paintings are both called "the Virgin of the Rocks". They show a scene of the Virgin Mary and the child Jesus in a rocky mysterious landscape. Mary and Jesus are meeting with John the Baptist. There is a story (which is not in the Bible but is part of Christian tradition) about how the baby John and the baby Jesus met on the road to Egypt. In this scene John is praying and the baby Jesus raises his hand to bless John. The paintings have a strange eerie light with soft deep shadows. In the background is a lake and mountains in the mist. No painting like this had ever been done before.
Leonardo's other important painting in Milan is even more famous. It is the "Last Supper". The painting shows the last meal shared by Jesus with his disciples, before his capture and death. Leonardo chose to paint the moment when Jesus has said "one of you will betray me". Leonardo tells the story of the surprise and upset that this caused to the twelve followers of Jesus. He tells the story through the actions and faces of the people in the painting. Some of them are talking, some of them have stood up, some are raising their hands in horror.
The novelist Matteo Bandello saw Leonardo at work. Bandello wrote that on some days he would paint from morning till night without stopping to eat. Then for three or four days he would not paint at all. He would often just stand and look at the painting. Vasari said that the prior of the convent was very annoyed. He asked Ludovico to tell Leonardo to work faster. Vasari said that Leonardo was worried because he did not think that he could paint the face of Jesus well enough. Leonardo told the Duke that he might use the face of the prior as his model for Judas, the traitor.
When it was finished, everyone that saw it said that the painting was a masterpiece. But Leonardo had not used proper fresco for the painting. He had used tempera over gesso, which is not usually used for wall painting. Soon the painting started to grow mold and flake off the wall. In a hundred years it was "completely ruined".
Even though in some places the paint has fallen right off the wall, the painting is so popular that it is printed and copied more that any other religious painting in the world.
In 1499, Ludovico il Moro was overthrown. Leonardo left Milan with his servant Salai and a friend, Luca Pacioli, who was a mathematician. They went to Venice. Leonardo worked as a military architect and engineer. Because Venice is a city on many islands, Leonardo tried to think of ways to defend the city from a naval attack.
In 1500, Leonardo went back to Florence, taking his "household" of servants and apprentices with him. The monks from the monastery of "The Holy Annunciation" gave Leonardo a home and a large workshop. In 2005, some buildings which were used by the Department of Military Geography were being restored. The restorers discovered that part of the building was Leonardo's studio.
Leonardo started work on a new painting. He drew a large "cartoon". (This means a drawing that is a plan for the painting.) The cartoon showed the Virgin Mary sitting on the knee of her mother, St Anne. Mary holds the baby Jesus in her arms. Jesus stretches out his hands to his young cousin John the Baptist. Vasari says that everyone was so amazed by the beautiful drawing that "men and women, young and old" came in large groups to see it "as if they were attending a great festival". The drawing is now in the National Gallery, London. Even though it is old and faded and is kept in a dark room, people go to the gallery to sit in front of it every day. Like many of Leonardo's projects, the painting was never done.
In 1502 and 1503, Leonardo worked for Cesare Borgia, a powerful noble who was the son of Pope Alexander VI. Leonardo travelled around Italy with Borgia, as a military architect and engineer. Late in 1503, Leonardo returned to Florence. He rejoined the Guild of St Luke.