"By convention sweet and by convention bitter, by convention hot, by convention cold, by convention colour: in reality atoms and void."Democritus was born in Abdera in the north of Greece. Very little is known of his life, although he is said to have travelled to Egypt and Persia. Diogenes Laertius quotes him as saying: "I came to Athens and no-one knew me." Plato makes no mention of him but Aristotle credits him with the originating of the theory of Atomism. He wrote well over fifty books on subjects as various as ethics, physics, mathematics, music, literature, logic and language. Yet very few genuine fragments of his work survive and his long lasting effect on western science and philosophy has been via Epicurus.(FrB125 - in "Sextus Empiricus")
Where the Eleatic school (Parmenides, Zeno) argued that reality was one and indivisible, and not-being was impossible, Democritus envisaged many indivisible particles or atoms in constant motion in a void. For him, both being and non-being together were necessary to explain the world of change and motion, generation and decay as it is experienced. Atoms moving in the void were infinite in number, and varied in size and shape. Each was indivisible but capable of connecting with others to form larger entities - the visible bodies of the world. Democritus explained sense perception and thought in terms of different shapes, interactions and amassing of atoms. The soul and fire atoms, for instance, were spherical and the most mobile and penetrative. Objects of perception are thought and believed to exist, but they do not exist in truth - only atoms and void do.