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

Thales

Thales of Miletus was a pre-Socratic Greek philosopher from Miletus in Asia Minor, and one of the Seven Sages of Greece. Many, most notably Aristotle, regard him as the first philosopher in the Greek tradition...

, who believed that everything was composed of water; Anaximander

Anaximander

Anaximander was a pre-Socratic Greek philosopher who lived in Miletus, a city of Ionia; Milet in modern Turkey. He belonged to the Milesian school and learned the teachings of his master Thales...

, who believed it was apeiron

Apeiron (cosmology)

Apeiron is a Greek word meaning unlimited, infinite or indefinite from ἀ- a-, "without" and πεῖραρ peirar, "end, limit", the Ionic Greek form of πέρας peras, "end, limit, boundary".-Apeiron as an origin:...

; and Anaximenes

Anaximenes of Miletus

Anaximenes of Miletus was an Archaic Greek Pre-Socratic philosopher active in the latter half of the 6th century BC. One of the three Milesian philosophers, he is identified as a younger friend or student of Anaximander. Anaximenes, like others in his school of thought, practiced material monism...

, 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

Albert Einstein

Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

, 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 atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s and even quark

Quark

A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...

s.