Soranus of Ephesus, a 2nd-century Greek gynecologist, was Hippocrates' first biographer and is the source of most personal information about him. Later biographies are in the Suda of the 10th century AD, and in the works of John Tzetzes, which date from the 12th century AD. Hippocrates is mentioned in passing in the writings of two contemporaries: Plato, in "Protagoras" and "Phaedrus", and, Aristotle's "Politics", which date from the 4th century BC.