Philosophy named from the Stoa, or portico, in Athens where its adherents gathered.
It was founded by Zeno of Citium (c.336-c.264 BC) - different from Zeno the Elea - but considerably developed by his successors, notably: Chrysippus (c.280-c.206 BC), Posidonius (C.135-C.51 BC), Seneca 'the Younger' (c.4 BC-AD 65), Epictetus (C. AD 50-138).
The Stoics divided philosophy into three branches, logic, physics, and ethics. In logic they went substantially beyond Aristotle (384-322 BC), inventing the propositional calculus.
In physics (which included metaphysics) they developed a pantheistic but materialist and determinist system contrasting with Epicurean atomism. In ethics they aimed at self-sufficiency and acceptance of fate, treating 'virtue' as the only real value, though among the remaining things ('indif-ferents') some were 'preferred'.
A A Long and D N Sedley, The Hellenistic Philosophers (1987)