In the 4th century BC, Zeno of Elea (the heyday was about 464-461 BC) put forward an argument about the impossibility of motion, which is called "Zeno's paradox" in history. (1) Dichotomy. Suppose you want to reach the goal of a certain distance, before you can cross the whole of the distance and reach the goal, you must first cross half of this distance; before, you must cross half of this half; One has to go through the half of this half; and so on, to infinity. Since you can't cross an infinite number of points in a finite amount of time, you can't even start moving, much less reach your goal. (2) Achilles cannot catch up with the tortoise. Olympic distance running champion Achilles races against the tortoise, which crawls a distance first. Before Achilles can catch up with the tortoise, he must first reach the tortoise's starting point. During this time, the tortoise crawls another distance. Achilles had to catch up to this distance again, while the tortoise crawls another distance during this time. So, Achilles got closer and closer to the tortoise, but could never catch up with it (3). Every thing, when it occupies a space equal to itself, is at rest. And the flying arrow occupies a space equal to itself at any particular moment, so the flying arrow is stationary.