Aristotle, like many other philosophers, attacked Democritus and Leucippus theory of atoms. He believed more on the fact that everything was composed out of fire, water, earth, and air like his predecessors. That these four elements combined to form everything and that two forces acted upon it. One was Levity which made fire and air rise. And the other was gravity which made Earth and water sink. It would take another 2000 years for Democritus theory to be revived.