Simmias the Theban was a wealthy member of Socrates' close circle of friends. Originally a student of the Italian Pythagorean philosopher, Philolaus, he later became an associate of Socrates and was present on the day of his death. On that day the topic of discussion was the immortality of the soul (how appropriate), a dialogue that is recorded in Plato's Phaedo. In it Simmias articulates the Pythagorean  doctrine of the soul. In another Platonic dialogue, the Phaedrus, Simmias is praised highly for his philosophical abilities.