[2] He was a pupil of Diogenes of Babylon and Antipater of Tarsus in Athens, before moving to Rome where he did much to introduce Stoic doctrines to the city, thanks to the patronage of Scipio Aemilianus.

[3] He is said to have been a pupil of the linguist Crates of Mallus,[4] who taught in Pergamum, and moved to Athens where he attended the lectures of Critolaus and Carneades, but attached himself principally to the Stoic Diogenes of Babylon and his disciple Antipater of Tarsus.

[10] Both Panaetius and Polybius accompanied him on the Roman embassy that Scipio headed to the principal monarchs and polities of the Hellenistic east in 139–138 BC.

In Physics he gave up the Stoic doctrine of the conflagration of the universe;[17] tried to simplify the division of the faculties of the soul;[18] and doubted the reality of divination.

[16][20] Panaetius attempted to bring the ultimate goal of life closer to natural impulses,[21] and to show by similes the inseparability of the virtues.

[29] He followed his colleague Polybius in seeing the Roman republic as an ideal combination of the three traditional forms of rule, incorporating the best of monarchy, aristocracy and democracy without falling in their shortcomings.

The third investigation he had expressly promised at the end of the third book, but had not carried out;[32] and his disciple Posidonius seems to have only timidly and imperfectly supplied what was needed.

[40] Generally speaking, Panaetius, following Aristotle, Xenocrates, Theophrastus, Dicaearchus, and especially Plato, had softened down the severity of the earlier Stoics, and, without giving up their fundamental definitions, had modified them so as to be capable of being applied to the conduct of life, and clothed them in the garb of eloquence.