ethics of self-determination. Marcus Aurelius (121-180). Stoic . [ edit ] 200-400 CE Sextus Empiricus (fl. during the 2nd and possibly the 3rd centuries CE). Skeptic , Pyrrhonist . Plotinus (c. 205 - 270). Neoplatonist . Had a holistic metaphysics. Porphyry (c. 232 - 304). Student of Plotinus. Iamblichus of Syria