Illustration of a bust of Greek philosopher Democritus and the father of atomic theory. Democritus published works on ethics, physics, mathematics, cosmology and music. Very little has survived but his theories are known through commentaries on his work by later philosophers. In his atomic theory he stated that matter is made up of tiny indivisible particles called atoms. The properties of different substances were determined by the physical features of the atoms. For instance, atoms of water were smooth and round whilst atoms of fire were thorny. He believed that the motion of atoms was dictated by definite universal laws of nature and not by the will of the Gods. Print of a series of