The decision to give them walls to decorate in Florence's Great Council Hall pitched them directly against one another. Michelangelo's Battle of Cascina was a call to arms, Leonardo's Battle of Anghiari a pacifist manifesto. Neither picture was completed- and neither survives except in preliminary sketches and copies. Jonathan Jones uses this story of competition and confrontation as the focus for a wide-ranging exploration of the Florentine High Renaissance.
Nothing I've read about Leonardo and Michelangelo has ever given me such a clear and convincing idea of what these two sacred monsters stood for- and what they were like as people.