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Democritus (Greek: Δημόκριτος, Dēmokritos, chosen of the people) was a Greek mathematician and philosopher, most famous for his atomic theory of the universe.

Also cited by Archimedes as having discovered the formula for the volume of a cone as being one third the volume of a cylinder of the same base and height, and the similar formula for the volume of a pyramid.

He was not the first to suggest the atomic theory -- both Leucippus and Anaxagoras had come up with the idea earlier -- but Democritus made a more systematic and detailed vision.

He was apparently hated by Plato, who was jealous of him, and wished to burn all his writings.




  • Born: c. 460 BCE, Abdera, Thrace, Greece
  • Died: c. 370 BCE

Theorems and Definitions


All of these works have been lost, except for a few hundred fragments preserved as isolated sentences or paragraphs from quotes from the writings of others.

  • Pythagoras
  • On the Disposition of the Wise Man
  • On the Things in Hades
  • Tritogenia
  • On Manliness or On Virtue
  • The Horn of Amaltheia
  • On Contentment
  • Ethical Commentaries
Natural science
  • The Great World-Ordering (may have been written by Leucippus)
  • Cosmography
  • On the Planets
  • On Nature
  • On the Nature of Man or On Flesh (two books)
  • On the Mind
  • On the Senses
  • On Flavours
  • On Colours
  • On Different Shapes
  • On Changing Shape
  • Buttresses
  • On Images
  • On Logic (three books)
  • Heavenly Causes
  • Atmospheric Causes
  • Terrestrial Causes
  • Causes Concerned with Fire and Things in Fire
  • Causes Concerned with Sounds
  • Causes Concerned with Seeds and Plants and Fruits
  • Causes Concerned with Animals (three books)
  • Miscellaneous Causes
  • On Magnets
  • On Different Angles or On the Contact of a Circle and a Sphere
  • On Geometry
  • Geometry
  • Numbers
  • On Irrational Lines and Solids (two books)
  • Planispheres
  • On the Great Year or Astronomy (a calendar)
  • Contest of the Waterclock
  • Description of the Heavens
  • Geography
  • Description of the Poles
  • Description of Rays of Light
  • On the Rhythms and Harmony
  • On Poetry
  • On the Beauty of Verses
  • On Euphonious and Harsh-sounding Letters
  • On Homer
  • On Song
  • On Verbs
  • Names
Technical works
  • Prognosis
  • On Diet
  • Medical Judgment
  • Causes Concerning Appropriate and Inappropriate Occasions
  • On Farming
  • On Painting
  • Tactics
  • Fighting in Armor
  • On the Sacred Writings of Babylon
  • On Those in Meroe
  • Circumnavigation of the Ocean
  • On History
  • Chaldaean Account
  • Phrygian Account
  • On Fever and Coughing Sicknesses
  • Legal Causes
  • Problems

Notable Quotes

I would rather discover one cause than gain the kingdom of Persia.

Critical View

While the philosophy of Plato and Aristotle was noised and celebrated in the schools amid the din and pomp of professors, this of Democritus was held in great honour with the wiser sort.
-- Francis Bacon