Atomism (from Greek ἄτομον, atomon, i.e. "uncuttable, indivisible") is a natural philosophy proposing that the physical world is composed of fundamental indivisible components known as atoms. According to some twentieth-century philosophers, unit-point atomism was the philosophy of the Pythagoreans. It stated that atoms were infinitesimally small ("point") yet possessed corporeality. The Pythagorean philosophy was uncannily accurate in depicting the monad as the ultimate particle, now proven correct by scores of physicists as the indivisible particle of the aether of space. Atoms were considered as centres of force: dynamic particles. Monad (from Greek μονάς monas, "singularity" in turn from μόνος monos, "alone")[1] refers, in cosmogony, to the Supreme Being, divinity or the totality of all things. The concept was conceived by the Pythagoreans and refers to a single source acting alone, or to an indivisible origin, or to both. The concept was later adopted by other philosophers, such as Gottfried Wilhelm Leibniz, who referred to the monad as an elementary particle.

References to the concept of atomism and its atoms appeared in both ancient Greek and ancient Indian philosophical traditions. The ancient Greek atomists theorized that nature consists of two fundamental principles: atom and void. Unlike their modern scientific namesake in atomic theory, philosophical atoms come in an infinite variety of shapes and sizes, each indestructible, immutable and surrounded by a void where they collide with the others or hook together forming a cluster. Clusters of different shapes, arrangements, and positions give rise to the various macroscopic substances in the world.

The particles of chemical matter for which chemists and other natural philosophers of the early 19th century found experimental evidence were thought to be indivisible, and therefore were given by John Dalton the name "atom", long used by the atomist philosophy. Although the connection to historical atomism is to some modern thinkers as tenuous, elementary particles have become a modern analogue of philosophical atoms.

This course is presented as a primer, as its philosophical principles makes it easier to study, modern natural physics. The course includes studies on Pythagorean philosophy on numbers and music as presented on audio lecture by the illustrious Manly P. Hall.