Democritean School of Ancient Greek Philosophy Texts

The Democritean tradition begins with Democritus of Abdera, active in the late 5th and early 4th centuries BCE, who systematised the physical theory of his teacher Leucippus, the first to propose atomism. The school offered a materialist account of the world, framed in answer to Eleatic arguments against change and plurality.

Reality, on this account, consists of two fundamental principles: void, which is empty space, and atoms (ἄτομοι), physically uncuttable particles. Atoms are eternal, indestructible, and infinite in number; they vary in shape and size and are in constant motion through the void. Every perceptible object and all its perceived qualities result from atomic collisions, entanglements, and arrangements.

The ψυχή is itself composed of fine, spherical, and highly mobile atoms. Perception works through εἴδωλα, thin films of atoms shed from objects that strike the ψυχή-atoms. The cosmos is mechanistic: every event has antecedent atomic causes, and none serves a purpose or answers to divine guidance. The ethical ideal is εὐθυμία, cheerfulness, reached through moderation, study, and understanding of the way things are.

The tradition's lineage runs from Leucippus, active around 440–430 BCE and otherwise little known, to Democritus, the primary expositor, credited with more than seventy works and responsible for the theory's comprehensive form. Nausiphanes carried the teaching forward as the teacher of Epicurus, the tradition's most consequential successor, who adopted and modified atomism in the late 4th century BCE as the basis of his own school.

After Democritus the tradition persisted in the shadow of Platonism and Aristotelianism; Aristotle engaged with its physics but rejected it. The Epicurean school became the main vehicle for transmitting atomist ideas, and the Roman poet Lucretius set them out in his <cite>On the Nature of Things</cite>. With the decline of pagan philosophy the tradition faded until the Renaissance rediscovery of Lucretius's poem, which went on to shape early modern scientific thought.