School of Athens is a fresco by the Italian Renaissance artist Raphael. It depicts many of the great Greek philosophers. The original is at the Apostolic Palace in the Vatican. The central figures are Plato (L) and Aristotle (R):

It is commonly thought that their postures reflect their philosophy, with Plato pointing upwards in apparent reference to his Theory of Forms, while the right hand of his student Aristotle makes a level gesture, in reference to his emphasis on empiricism. Plato’s teacher, Socrates, can be found towards the left side, wearing a green robe and lecturing:

The gentleman lounging on the steps is the great Cynic, Diogenes of Sinope:

Epicurus can be found on the left side: