As “a major philosophical figure of the Roman Imperial Period”, Seneca’s lasting contribution to philosophy has been to the school of Stoicism. His writing is highly accessible and was the subject of attention from the Renaissance onwards by writers such as Michel de Montaigne. He has been described as “a towering and controversial figure of antiquity” and “the world’s most interesting Stoic”.

Seneca wrote a number of books on Stoicism, mostly on ethics, with one work (Naturales Quaestiones) on the physical world. Seneca built on the writings of many of the earlier Stoics: he often mentions Zeno, Cleanthes, and Chrysippus; and frequently cites Posidonius, with whom Seneca shared an interest in natural phenomena. He frequently quotes Epicurus, especially in his Letters.

Ten plays are attributed to Seneca, of which most likely eight were written by him. The plays stand in stark contrast to his philosophical works. With their intense emotions, and grim overall tone, the plays seem to represent the antithesis of Seneca’s Stoic beliefs. Up to the 16th century it was normal to distinguish between Seneca the moral philosopher and Seneca the dramatist as two separate people. Scholars have tried to spot certain Stoic themes: it is the uncontrolled passions that generate madness, ruination, and self-destruction. This has a cosmic as well as an ethical aspect, and fate is a powerful, albeit rather oppressive, force.

Works attributed to Seneca include a dozen philosophical essays, one hundred and twenty-four letters dealing with moral issues, nine tragedies, and a satire, the attribution of which is disputed. His authorship of Hercules on Oeta has also been questioned.

1. De Providentia (On providence) - addressed to Lucilius
2. De Constantia Sapientis (On the Firmness of the Wise Person) - addressed to Serenus
3. De Ira (On anger) – A study on the consequences and the control of anger - addressed to his brother Novatus
4. Ad Marciam, De consolatione (To Marcia, On Consolation) – Consoles her on the death of her son
5. De Vita Beata (On the Happy Life) - addressed to Gallio