Answer: An Illusion.
Explanation: One of the most celebrated paradoxes in the history of philosophy is that which tells the story of the Greek hero Achilles and the tortoise. It is said that Achilles, running a race with a tortoise, in a rush of generosity, decided to give her a small advantage, letting the animal break a few inches in front of him. According to the Greek philosopher Zeno, as fast as Achilles moved, he could never get past the tortoise. The paradox formulated by Zeno is this: each time Achilles travels a certain distance within a given time, the turtle has already traveled another distance
What Zeno was doing was to demonstrate that the movement of objects is an unrealistic and contradictory phenomenon, always consisting of mere illusion of the senses.