What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa?

Galileo Galilei is dropped two spheres of different masses from the leaning tower of pisa to demonstrate that their time of descent was independent of their mass.he discovered that the objects fell with the same acceleration, proving his prediction true.he predicted that bodies of same material falling through the same medium would fall at the same speed. Imagine two objects, one light and one heavier than the other one, are connected to each other by a string. Drop this system of objects from the top of a tower. If we assume heavier objects do indeed fall faster than lighter ones ,the string will soon pull tightly stretched as the lighter object retards the fall of the heavier object. But the system considered as a whole is heavier than heavy object alone, and therefore heavier one will fall faster than lighter one.This contradiction leads one to conclude the assumption is false. He disproves the “Aristotle theory of gravity states that heavy objects fall faster than lighter ones, in direct proportion to weight or which states that objects fall at speed proportional to their mass.