"Euthyphro" is a philosophical dialogue that takes place in the weeks leading up to the trial of Socrates, where Socrates and Euthyphro engage in a conversation about the nature of piety. The dialogue begins with Socrates questioning Euthyphro about his decision to prosecute his own father for the murder of a slave. This leads to a discussion about what is considered holy and the nature of the gods. Despite their lengthy conversation, the two philosophers never arrive at a definitive answer, leaving the question of what constitutes true piety unresolved.

The 2634th greatest book of all time