In 1971, angina pectoris forced Stone to cease publication of the "Weekly". After his retirement, he returned to the University of Pennsylvania, where he had dropped out years before. He earned a bachelor's degree in classical Languages. Stone successfully learned Ancient Greek and wrote a book about the prosecution and death of Socrates, "The Trial of Socrates", in which he argued that Socrates wanted to be sentenced to death in order to shame Athenian democracy, which he despised. "The Trial of Socrates" was a "New York Times" bestsellerand was translated into 11 languages.