Cicero is one of the Roman gems that people tend to miss out on. He lived more than 2000 years ago, and written many works on Greek philosophy (including the works of Plato, Stoics, Epicureans, et al); and some of his own. He often claims that he doesn't take sides, but aims for what is most "probable". Although, in some cases he leans heavily towards Stoic ethics (despite his love for Plato's Academy).

Besides the "On Old Age", some recommended English translations of his works:

• On Duties — this volume is divided into three 'books'; the first 'book' covers Stoic ethics in highly compressed form. Recommended English translation: "Cicero On Duties (Cambridge Texts in the History of Political Thought)"; it also has very useful footnotes.

• Tusculan Disputations — horrendous name (more correctly called: "Discussions at my villa in Tusculum"), but excellent content. It covers five themes ("disputations"); two of them written when Cicero was grieving from the sudden death of his daughter. I suggest these two translations, which cover the five themes: (a) "On Life and Death" (Oxford World's Classics); translation by John Davie; – this covers the themes 1, 2, 5, and other essays; and (b) "Cicero Emotions", by Margaret Graver – this brilliant volume covers the 4th and 5th disputations, with unparalleled commentary by Graver.

Bonus: "On the Good Life" (Penguin Classics) also reads well. It has two parts from "On Duties", and a few essays by Cicero, including one on friendship.