Leonardo began the formal study of the topographical anatomy of the human body when apprenticed to Verrocchio. He would have been taught to draw the human body.
Leonardo illustrated a book on mathematical proportion in art written by his close friend Luca Pacioli and called De divina proportione, published in 1509.
Leonardo kept a series of journals in which he wrote almost daily, as well as separate notes and sheets of observations, comments and plans. He wrote and drew with his left hand.