( 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.
( Circa 335-circa 263 bc), Greek philosopher, founder of Stoicism; known as Zeno of Citium. He founded the school of Stoic philosophy (circa 300) (see stoicism), but all that remains of his treatises are fragments of quotations.