Cicero: On Duties (De Officiis)

The major schools of thought at this time were the Academic, Stoic, Epicurean, and Peripatetic. The Academic school was founded by Plato around 385 BC and practiced skepticism. The Stoics, founded by Zeno around 300 BC, held virtue to be the greatest human good. Epicureans, founded by Epicurus around 307 BC, associated goodness with pleasant physical experiences, and believed life centered around sensually-pleasing things. Finally, the Peripatetics, with whom Cicero's son studied, were founded in 335 BC by Aristotle, and existed between Stoics and Epicureans in their belief that sensual pleasure was good, but that virtue was the highest good. Cicero's own writings follow Panaetius, a Peripatetic philosopher, and tend to fall in line with their teachings. 

Three schools of thought compete in Cicero's philosophical landscape to formulate a concept of human nature. The Peripatetics believed that the universe emanated from a single, perfect being, whom humans tried to imitate. They valued the human mind above bodily pleasures, but did not deny the value of the latter. The Stoics believed in a universe ruled by a material, divine mind. They valued virtue above all, and believed that a wise person lived in accordance with human and universal nature.