In 1506, Leonardo was summoned back to Milan by Charles d'Amboise, French governor of Lombardy. Now an international celebrity, the artist was in high demand; and after his move, the Florentine government often sent letters to d'Amboise, petitioning the French to let Leonardo return to Florence. They wanted him to complete the Battle of Anghiari, which they had already paid for. As always, however, Leonardo gave preference to his own wishes, and this meant staying in Milan, a city where he had always felt comfortable.
The Confraternity of the Immaculate Conception, which had originally commissioned the Virgin of the Rocks, had for a long time been involved in legal battles with the brothers de' Predis, who had painted the side panels. Now, Leonardo had to return to the painting and supervise a new version. He may have done some of the actual work himself, as well; some critics think they see his hand in the angel's face. Certainly, his changing style is seen in the more aged and large-bodied Mary.
In general, Leonardo's fortunes were on the rise. He soon became painter and engineer to Louis XII, King of France. In 1507, while traveling in the surrounding countryside, Leonardo met the young Francesco Melzi. The boy was 15 years old. Melzi, a thick-haired boy with almond-shaped eyes, became one of Leonardo's most beloved "pupils," along with Salai.
Later that year, in 1507, Leonardo had to return to Florence: when his father had died without a will, in 1504, his legitimate sons had claimed all of the inheritance; now, Leonardo's uncle Francesco had died, and had left a large amount to Leonardo. However, Leonardo's brothers again tried to cut Leonardo out of his share, and this time Leonardo took them to court. He even had Louis XII write to the court officials in Florence to speed up the legal proceedings. The dealings lasted nearly six months.
Both while still in Florence and then while back in Milan, Leonardo increased work on his anatomical studies. He sketched practically every organ in the body, each one from different angles–an unusually modern technique for the sixteenth century. Leonardo also seriously engaged himself in studies of hydraulics.
Leonardo's interest in anatomy probably led to an interest in illustrating the myth of Leda and the Swan. According to the myth, Zeus assumed the form of a swan in order to seduce and impregnate the beautiful Leda. Such an intense scene of bodily struggle between beast and human no doubt fired Leonardo's anatomically oriented imagination.