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History of Science Ancient Egypt

History of Science Online

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LibraryThing: Science in Ancient Mesopotamia Week 3: Ancient Egyptian and Aegean science

The Atomists: Leukippos of Miletos (fl. 450 B.C.) and Demokritos of Abdera (fl. 420 B.C.)

| Presocratics Index | Intro | Thales | Anaximandros | Anaximenes | Herakleitos | Parmenides | Zenon | Melissos |
| Atomists: Leukippos and Demokritos | Anaxagoras | Empedokles | Significance of the Presocratics |

The work of the Roman poet Lucretius, On the Nature of Things, was rediscovered in the 1400's in a monastery by a scholar who was searching for a surviving copy. It remains the only source of information about earlier Greek atomists, other than the hostile quotations in Aristotle and other ancient sources. Demokritos of Abdera said that everything he knew he learned from his teacher, Leukippos of Miletos. Yet no works of either survive.

Parmenides of Elea argued that the universe is a plenum, completely filled with matter. But the problem arises: If the universe is a plenum, with no empty spaces for things to move into, then how can motion be possible? Parmenides' answer was that our senses deceive us! This was the challenge of Parmenides, to come up with an account of change that would withstand logical scrutiny. Eventually, Aristotle's answer, known as anti-peristasis, would prevail. By this term Aristotle meant that things would move simultaneously into the spaces left by other things in a loop of mutual replacement. Thus one could account for change within a plenum. Yet before Aristotle and the idea of anti-peristasis, Leukippos and Demokritos rescued the idea of change by denying the plenum in the first place, and asserting the existence of one of the most controversial of concepts in the history of science: the void.

According to Leukippos and Demokritos, the universe consists of many small, imperceptible, separate pieces too tiny to see, each of which is an indivisible, miniature plenum. Since they are indivisible, being plenums, they are called atoms (tome = to divide). Since they are separate there must be empty space, a void, between them. Demokritos and Leukippos clearly rejected the monistic view of nature. For them, nature consists of two realities:

Only atoms and the void are real. Changes in nature result from the random motion of atoms in the void, aggregating or splitting apart to comprise the objects we can detect with our senses.

The inifinite number of atoms differ in size and shape but not in substance. The changing appearances we observe in nature are due to changes in the arrangements of atoms. The void permits movement of atoms and allows for change. Coming-to-be or passing-away results from the separation of atoms as they move through the void and combine into new arrangements. Thus the atomists created a possible response to the challenge of Parmenides.

Our sensory perceptions, however, do not provide direct experience of the primary aspects of atoms (e.g., their shape and size). That is, the secondary qualities of things we perceive (such as taste) are not the primary aspects of atoms. Our senses deceive us by producing the impression of secondary qualities which are not the primary attributes of things. That is, "sourness" and "sweetness" are not inherent in the nature of things themselves, but are produced by our sensations. For example, small and angular shaped atoms produce an acid taste, while sweetness is caused by large, round atoms. But it is only the shape of an atom, not its taste, that gives rise to our perception of a subjective quality we know as taste. This separation between primary reality and secondary qualities of things was rejected by Aristotle, as we shall see.

More importantly, atomism was consistently rejected by ancient natural philosophers because of its insistence on the possibility of a void. For how can nothing exist? How can nothing be something? How can what is, be what is not? When philosophers advocating continuous matter developed the idea of antiperistasis, they no longer needed the answer of the atomists to respond to Parmenides' challenge. And their objection to the atomists, “How can what is consist of what is not?”, seemed unanswerable by the atomists. The atomists represented one possible answer that became the “road not traveled.”

First principle
Thales of Miletos
Anaximandros of Miletos
Anaximenes of Miletos
Herakleitos of Ephesos

Parmenides of Elea,
Zenon of Elea,
Melissos of Samos


Monism, Plenism, Rationalism, Necessitarianism, Sufficient Reason, Akinesis, Eternity of the World

Leukippos of Miletos and Demokritos of Abdera Atoms + Void Pluralism, Void, Tychism

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HSCI 3013. History of Science to 17th centuryCreative Commons license
Kerry Magruder, Instructor, 2004
Brent Purkaple, TA

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Many thanks to the pedagogical model developed in Mythology and Folklore and other online courses by Laura Gibbs, which have been an inspiration for this course.

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