How did Democritus created the Theory of Matter?

Therefore, changes in matter were a result of dissociations or combinations of the atoms as they moved throughout the void. Although Democritus' theory was remarkable, it was rejected by Aristotle, one of the most influential philosophers of Ancient Greece; and the atomic theory was ignored for nearly 2,000 years. read more

His mentor, Leucippus, originally came up with the atomic theory, but it was then adopted by Democritus. The atomic theory stated that “The universe is composed of two elements: the atoms and the void in which they exist and move.” According to Democritus atoms were miniscule quantities of matter. read more

He didn't. He inherited (& developed) the idea from Leucippus. Both were arguing against the philosophy espoused by Parmenides and Zeno, which argued motion was impossible and thus the world we see an illusion. read more

According to Democritus' atomic theory, everything is made up of atoms, which are physically indivisible: atoms are indestructible, eternal and invisible, small and unable to be diminished. He posited that atoms occupy space and differ in size, shape, magnitude, position and arrangement. In his model, atoms are homogeneous. read more