Leonardo's conception of man and nature was quintessentially dynamic. Nature is the theater of incessant phenomena of transformation, governed by the same laws to which mankind and all living organisms are subject. His tendency to bring human emotions too within the framework of a strictly naturalistic approach led to the intense physical analysis of the "moti mentali" that inspired his representations of human features in drawings and paintings.
For Leonardo, understanding the causes of motion by systematically investigating its manifestations was the only way to discover the rigorous laws that govern nature. This knowledge is indispensable to the painter who strives to imitate its splendid works.