But apparently some of my conceptions about his thinking were the result of bad capsule explanations, too: while Aristotle did think that heavier objects fell faster than lighter ones, his explanation was a little more sophisticated than that, being that the speed of a falling object was the result of a constant, the weight of the object, and the density of the fluid it was falling through - and apparently this is actually not such a bad approximation for human-scale stuff falling through air or water.
But just the other day I learned about John Philoponus, a 6th-century thinker who had much more correct ideas about matter, inertia, and the nature of the universe. He was one of the first to hold that the heavens and the earth have the same physical properties, and the stars are not divine, and he viciously took down Aristotle's theories on motion and falling objects:
But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small.