Plato, often hailed as the greatest philosopher who ever lived, has not, until now, been given a full-length biography. The problem is a lack of primary sources, says Robin Waterfield, a scholar and ...

Diogenes of Sinope, a beggar who lived on the streets of Athens in the fourth century B.C.E., has been hailed as the progenitor of performance art, an inspiration for the Occupy movement, and, by the ...