Hero's Formula (2005-Present) Calculus began with Zeno's paradoxes about time, motion, and change. The most famous one is about Achilles and the tortoise. Consider a race between the great warrior and a humble tortoise in which the creature is given a head start. By the time Achilles reaches the tortoise's starting place, the tortoise has crawled a bit farther ahead. By the time Achilles gets there, the tortoise has moved a little more and hence is still in the lead. Thus, a swift runner can never overtake a slower one. Since common sense says otherwise, Zeno con- cludes that common sense is wrong. Change is an illusion.