Lives of Eminent Philosophers, Volume 1 by Diogenes Laertius ( - 3rd Cent.)

Diogenes Laertius' Lives of Eminent Philosophers provides a wealth information about the lives and teachings of ancient Greek thinkers. Despite the varying reliability of Laertius' accounts, his book has become a principal source for the history of Greek philosophy, since many of the earlier sources on which it was based are no longer extant. - Summary by Kazbek