Leucippus
480?-420? B.C.
Greek Philosopher
It may surprise many modern people to learn that the concept of the atom is an ancient one, but in fact it had its roots with the Greek philosopher Leucippus and his student Democritus (460?-370? B.C.). It is perhaps ironic that these two should have been responsible for the idea that all of nature can be broken down into infinitesimal and indivisible parts: likewise it is difficult to separate the contributions of Leucippus from those of his more famous pupil in forming the theory of atomism.
Details of any kind about Leucippus's career are scant, and this is particularly so with regard to his early life. It is possible he was born in Miletus, a town in Asia Minor (now Turkey) that was home to numerous philosophers and scientists. He may have founded the school of philosophy at the city of Abdera (now Advira) on the Thracian coast of Greece, and it seems fairly well established that he as least lived in Abdera.
Yet Epicurus (341-270 B.C.), writing less that two centuries later, maintained that Leucippus was only a legendary figure, since so little was known of his life. Even Aristotle (384-322 B.C.), who along with his own pupil Theophrastus (372?-287 B.C.) credited Leucippus with establishing the theory of atomism, seems to have been uncertain about Leucippus's role in developing atomic theory, at times suggesting that Democritus worked alone.
Some scholars have maintained that Leucippus studied under Zeno of Elea (495?-430?). It is more likely, however, that he was simply influenced by Zeno, as well as by Zeno's mentor Parmenides (b. 515? B.C.). Implicit in the paradoxes of Zeno is the idea that matter can be divided endlessly; but Leucippus maintained that the quality of divisibility does not continue endlessly. Rather, in Leucippus's view, at the smallest level of existence were indivisible monads too tiny to see.
In using the term atom, it should be stressed that Leucippus's understanding of atoms was different not only in degree, but in kind, from the understanding of atomic particles by physicists today. He had no concept of elements—not even the primitive idea of four elements, such as fire and water and so on. To him and to all thinkers of his time, all matter consisted of the same substance: individual atoms differed only in position and perhaps shape.
Nonetheless, Leucippus broke new ground by finding divisibility in nature, where up to that time scientists saw only an undifferentiated mass. His achievement becomes particularly impressive when viewed in light of the Greeks' tendency to regard empty space as nothingness, devoid of content. It was for this reason, for instance, that Greek architecture avoided the arch, which seemed to place an emphasis on the void rather than on the physical substance of the stone framing the void. Yet according to Theophrastus, it was Leucippus's position that both matter and void had an existence.
Leucippus was said to have been responsible for two texts, The Great World System and On the Mind. In fact only fragments of either survive, and then primarily through the works of others. In commenting on Leucippus, Diogenes Laertius (third century A.D.) indicated that The Great World System put forth a cosmology regarding the creation of worlds. It was Leucippus's view, Diogenes wrote, that worlds were created by the agglomeration of large atoms at the center—an explanation that sounds rather like a precursor to the law of gravity.
Along with Democritus, Leucippus has long enjoyed a reputation for astounding prescience, anticipating the subjects of twentieth century physics by a good 2,500 years. Perhaps even if he could see all that would unfold, Leucippus would not have regarded later discoveries as a surprise: in the single surviving direct quote from the teacher, he maintained that "Nothing happens in vain, but everything from reason and of necessity."
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