Materialism

2. Ancient Greek atomism

Although Leucippus is credited with inventing the atomic theory of matter in the fifth century bc, it was Democritus (fourth century bc) who developed a systematic theory of atomistic materialism. This theory states that matter is composed of separate and minute elements that are ‘uncuttable’ (atoma), that these elements move in empty space or the ‘void’. Atoms differ only in shape and volume, and all change occurs by the transfer through direct contact of movement from atoms in motion. These elementary entities are lacking in secondary qualities and are indestructible. Democritus held that things are hot or cold, sweet or bitter, or have different colours ‘by convention’. In reality, ‘there are atoms and the void’.

The essentials of early atomism were retained in Epicurus’ physics, with the exception that Epicurus ascribed freedom to atoms in their movement through space. Epicurean materialism is lucidly expressed in the philosophic poem by Lucretius, De rerum natura (On the Nature of Things), in the first century bc. This popularization of Epicurean thought did much to keep alive both atomistic materialism and what is already recognizable as a naturalistic understanding of humans and world (see Epicureanism).