Ancient people in many parts of the world believed that all matter was made of four elements: earth, air, water, and fire. No matter how small an amount of material you had, you could not separate an element into a combination of other materials. But if you kept dividing the amount of material into smaller and smaller pieces, what would you obtain?

Democritus, a Greek who lived around 410 B.C.E. and was the student of Leucip-pus of Miletus (ca. 435 B.C.E.), stated that all matter is made up of atoms and the void. Atoms are the smallest piece into which an element can be divided; they are uncut-table. They could be neither created nor destroyed, and thus were eternal. The void was empty space. This viewpoint was expanded by the first century B.C.E. by the Greek Titus Lucretius Carus (95-55 B.C.E.) in his epic poem “On the Nature of Things.” Aristotle, on the other hand, regarded the atomist philosophy as pure speculation that could never be tested. He rejected the possibility of empty space and believed you could divide matter until it was infinitely small.

The Greeks were not the only ones to develop a philosophy of atomism. The Indian school of philosophy known as Valsesika, and in particular the philosopher Kanada in the second century B.C.E., held that earth, air, fire, and water could be divided into a finite number of indivisible particles. These ideas were adopted by several other Indian schools of philosophy.