Material Monism

Material monism is a Presocratic belief which provides an explanation of the physical world by saying that all of the world's objects are composed of a single element. Among the material monists were the three Milesian philosophers: Thales, who believed that everything was composed of water; Anaximander, who believed it was apeiron; and Anaximenes, who believed it was air.

Although their ideas seem farfetched, these philosophers were the first to give an explanation of the physical world without referencing the supernatural; this opened the way for all modern science (and philosophy), which has the same goal of explaining the world without dependence on the supernatural.

Some modern theorists, such as Albert Einstein, have searched for a theory that explains the world as the product of a single substance, but at a deeper level, one that is beneath the structure of atoms and even quarks.