A drawing in red chalk widely accepted as a self-portrait of Leonardo da Vinci. Biblioteca Reale, Turin. Machiavelli collaborated with Leonardo on a plan to steal the river Arno from the Pisans, bringing them to their senses, or their knees, or both.

By the time he died, 500 years ago today, Leonardo da Vinci had long risen above the disadvantage of his illegitimate birth. His father was a wealthy (...)