Democritus, dih MOK rih tuhs (460?-370? B.C.), was a Greek philosopher. He argued that the world consisted of an infinite number of atoms moving in an infinite void. These atoms are invisible and indivisible particles of matter that were ungenerated and indestructible. They differ from one another in size, shape, and position. Each thing in the world is a different combination of these atoms. Our world came about as the chance combination of atoms, and since there are an infinite number of atoms, innumerable other worlds also have come to be.