490?-425? B.C.

Greek philosopher and student of Parmenides who is remembered chiefly for his paradoxes, which illustrate the nature of motion and time. Among the most famous of these is "Achilles and the tortoise," which posits that if Achilles and a tortoise were to race, with the much slower tortoise given a lead, Achilles could never overcome the tortoise, who would continue to outdistance Achilles, however marginally, as long as it continues to move. Another paradox, "the flying arrow," suggests that motion is impossible. Many thinkers since have been fascinated and frustrated by Zeno's paradoxes.