Impressed by the letter, Da Vinci is hired to advise the military and surveys aspects of his talent (Jardine, 243). During his employment he spent much time on "somber, symbolic, or jovial exhibits, creating temporary displays" for the royal court of Milan; these showed his capability in expressing his art (Holmes, 151). Da Vinci was not commissioned for very many projects so he worked on masterpieces such as the "Virgin of the Rocks, "Lady with an Ermine and "Last Supper" (Holmes, 150); here he finally fulfilled his true artistic talent. George Holmes calls Da Vinci "an autodidact who struggled through his like to absorb the scholarship of professional mathematics and philosophy and add to it" (151), using all the knowledge he could possibly acquire he wrote thousands of manuscripts consisting of his thoughts and reflections on science while trying to obtain more and stretch beyond their limits (Holmes, 150). This became a probable cause that led his works to "buckle under his strain of expectation" (Graham-Dixon, 164). From 1481-1500 the Duke of Milan protected Da Vinci against blacklisting and heresiarchs, which were consequences of his excessive indulgence into art and knowledge (Manchester, 91).
Da Vinci worked in other secular courts after his time with the Duke of Milan. One of his employers was the fanatic Cesare Borgia, who briefly hired Da Vinci as his military architect in 1502. Da Vinci inspected the strength and wealth of Borgia's possessions which included the territory he owned (Manchester, 91). It was in 1503 when he completed the Mona Lisa which George Holmes says that it's "dept of expression cannot be defined" and Da Vinci worked on the "Mona Lisa" for years "adding emotional dept and complexities unseen in the actual sitter (50). Leonardo's fall from papal grace started with his employment in secular courts, especially Borgia's, and extended to many other events and accomplishments that challenged the Catholic Church.
