Socrates

Socrates (469-399 B.C.) is a Greek philosopher from Athens. Along with Plato and Aristotle is one of the three great figures in Ancient philosophy. Plato, his most brilliant associate and pupil, is the main source of information about Socrates.
Socrates took part in three military campaigns of Athens and distinguished himself by his bravery, remarkable physical endurance and indifference to fatigue, climate and alcohol.
Otherwise he was detached from politics and examined “conventional moral attitudes and assumptions”. The ‘Socratic method’ was to ask for definitions of familiar concepts like justice, courage and piety, to draw out contradictions in the replies of his responders, and thus to demonstrate people’s ignorance, and the need for a deeper and more honest analysis. For this unpopular activity the Athenian government accused him in ‘impiety’ and ‘corrupting the youths’. He was tried at the age of 70; he was offered the choice of renouncing his beliefs or being sentenced to death by drinking hemlock.
He chose the latter, declined a later opportunity to escape from prison, and calmly took the poison.
See David Death of Socratus; David shows the moment when Socratus having accepted the death sentence is reasoning on the immortality of the soul before his followers.
See: Jacques-Louis David. The Death of Socrates.

Bibliography:
Chambers Biographical Dictionary. Chambers. 1996.
Lexikon der Antike. VEB Bibliographisches Institut Leipzig. 1987.