Socrates (c. 470–399 B.C.), the Greek philosopher who is credited, along with philosophers Plato (c. 428–347 B.C.) and Aristotle (384–322 B.C.), for laying the foundations of Western thought, had many followers in his own time. However, his ideas and methods were controversial, too, which led him to be tried before judges and sentenced to death, which he carried out by drinking hemlock (poison). He had been charged for not worshiping the Athenian gods and for corrupting the young.

Except for his time spent in military service, Socrates lived his entire life in Athens, where he was as well known for his disheveled appearance as for his moral integrity, self-control, and quest for wisdom. He lived during a time when attention was turning away from the physical world (of the heavens) and toward the human world (of the self, the community, and the law). He participated in this turning point by walking the streets of Athens, engaging people—including rulers who were supposed to be wiser than he—in conversation. In these conversations, he employed what came to be known as the “Socratic method” or dialectic, a series of seemingly simple questions designed to elicit a rational response. Through the line of questioning, which usually centered around a moral concept such as courage, the person being questioned was intended to realize that he did not truly know that which he thought he knew. Socrates’s theory was that once the person being questioned realized his weak understanding, he could divest himself of false notions, and was then free to participate in the quest for knowledge. These philosophical “disputes,” however, gained Socrates many enemies.

Though he left no writings, Socrates’s student, Plato, documented his recollections of dialogues with his teacher. A staunch believer in self-examination and self-knowledge, Socrates is credited with saying that “the unexamined life is not worth living” (some ascribe the quote to Plato). Socrates also believed that the psyche (or “inner self”) is what should give direction to one’s life—not appetite or passions. A seminal figure in Greek (and Western) thought, philosophy that predates him is termed “pre-Socratic.”