Panaetius of Rhodes was a pupil of Diogenes of Babylon and Antipater of Tarsus, both heads of the Stoic school in Athens, and he succeeded Antipater as scholarch in 129. Little is known about his life though it is clear that he spent considerable time in Rome and in the circle of P. Cornelius Scipio Aemilianus. None of his writings survive, but traces of his importance do.

First, isolated testimony from antiquity reveals that Panaetius was especially willing to disagree with earlier Stoics about central matters of doctrine. He rejected the Stoic belief in divination, and against the earlier account that the cosmos would be consumed periodically in flames, he insisted that the world is everlasting. He maintained that virtue is not sufficient for happiness, since health, some resources, and strength are also necessary, and he divided virtues into...