Dialogues of Plato — Jowett — Twenty-three dialogues of Plato in Benjamin Jowett's Oxford translation — the Apology, Crito, Phaedo, Phaedrus, Symposium, Gorgias, Meno, Ion, Republic extracts, Timaeus, Theaetetus, Parmenides, Sophist, Statesman, Philebus, and others.
Golden Verses of Pythagoras — Firth — The Golden Verses of Pythagoras and other Pythagorean fragments — the foundational ethical text of the Pythagorean school, with Hierocles' commentary and other fragments. Translated by Florence M. Firth (1904).
The Discourses of Epictetus — The Discourses of Epictetus, Books III and IV — recorded by Arrian of Nicomedia; translated by W. A. Oldfather. Loeb Classical Library, 1928. Practical Stoic philosophy on freedom, desire, discipline of assent, and the examined life.
The Meditations of Marcus Aurelius — The private philosophical notebooks of the Roman Emperor Marcus Aurelius — twelve books of Stoic reflection on duty, impermanence, reason, and the examined life, written in Greek during military campaigns on the northern frontier, circa AD 161–180.