(fl. 5th century BC), Greek philosopher. A member of the Eleatic school, he defended Parmenides' theories by formulating paradoxes which appeared to demonstrate the impossibility of motion, one of which shows that once Achilles has given a tortoise a start he can never overtake it, since each time he arrives where it was, it has already moved on.
(c.335–c.263 BC), Greek philosopher, founder of Stoicism; known as Zeno of Citium. He founded the school of Stoic philosophy (c.300), but all that remains of his treatises are fragments of quotations.