Leucippus

Leucippus (fl. 5th century BCE) was an early Greek philosopher, traditionally considered the originator of atomism. Very little is known about his life, and the details are often intertwined with those of his more famous student, Democritus. Some ancient sources even questioned whether Leucippus was a real historical figure.

While no writings are definitively attributed solely to Leucippus, he is credited, primarily by Diogenes Laërtius, with authoring several works, including "The Great World System" and "On Mind." These works are now generally believed to have been jointly produced with or heavily influenced by Democritus.

Leucippus's significance lies in his pioneering development of atomism, the theory that the universe is composed of indivisible, fundamental particles called atoms (ἄτομοι; atomoi, meaning "uncuttable") moving in a void. He posited that these atoms are infinite in number and differ in shape, size, position, and arrangement. These differences, according to the theory, account for the variety of macroscopic objects and phenomena we observe. Change, in this view, is due to the rearrangement of atoms.

Although his ideas were largely speculative and lacked empirical support, Leucippus's atomism represented a significant departure from earlier cosmological theories based on mythical explanations or the concept of a single, underlying substance. It laid the groundwork for later atomic theories developed by Democritus and, much later, by modern scientists. Leucippus's contribution is mainly recognized through the reports and interpretations of later philosophers, especially Aristotle, who frequently discusses and critiques the atomists' views.