III. LEUCIPPUS AND DEMOCRITUS.—Leucippus is variously called a native of Elea, of Abdera, of Melos, of Miletus. He was a pupil of Zeno the Eleatic. [144] Democritus was a native of Abdera. They seem to have been almost contemporary with Socrates. The two are associated as thorough-going teachers of the 'Atomic Philosophy,' but Democritus, 'the laughing philosopher,' as he was popularly called in later times, in distinction from Heraclitus, 'the weeping philosopher,' was much the more famous. [145] He lived to a great age. He himself refers to his travels and studies thus: "Above all the men of my time I travelled farthest, and extended my inquiries to places the most distant. I visited the most varied climates and countries, heard the largest number of learned men, nor has any one surpassed me in the gathering together of writings and their interpretation, no, not even the most learned of the Egyptians, with whom I spent five years." We {75} are also informed that, through desire of learning, he visited Babylon and Chaldaea, to visit the astrologers and the priests.
[146]
Democritus was not less prolific as a writer than he was voracious as a student, and in him first the division of philosophy into certain great sections, such as physical, mathematical, ethical, was clearly [147] drawn. We are, however, mainly concerned with his teaching in its more strictly philosophical aspects. His main doctrine was professedly antithetical to that of the Eleatics, who, it will be remembered, worked out on abstract lines a theory of one indivisible, eternal, immovable Being. Democritus, on the contrary, declared for two co-equal elements, the Full and the Empty, or Being and Nonentity. The latter, he maintained, was as real as the former. As we should put it, Body is unthinkable except by reference to space which that body does not occupy, as well as to space which it does occupy; and conversely Space is unthinkable except by reference to body actually or potentially filling or defining it.
What Democritus hoped to get by this double or correlative system was a means of accounting for or conceiving of change in nature. The difficulty with the Eleatics was, as we have seen, how to understand whence or why the transition from that which absolutely is, to this strange, at least apparent, system of eternal flux and transformation. Democritus {76} hoped to get over this difficulty by starting as fully with that which is not, in other words, with that which wants change in order to have any recognisable being at all, as with that which is, and which therefore might be conceived as seeking and requiring only to be what it is.
[148]
Having got his principle of stability and his principle of change on an equal footing, Democritus next laid it down that all the differences visible in things were differences either of shape, of arrangement, or of position; practically, that is, he considered that what seem, to us to be qualitative differences in things, e.g. hot or cold, sweet or sour, green or yellow, are only resulting impressions from different shapes, or different arrangements, or different modes of presentation, among the atoms of which things are composed.
Coming now to that which is, Democritus, as against the Eleatics, maintained that this was not a unity, some one immovable, unchangeable existence, but an innumerable number of atoms, invisible by reason of their smallness, which career through empty space (that which is not), and by their union bring objects into being, by their separation bring these to destruction. The action of these atoms on each other depended on the manner in which they were brought into contact; but in any case the unity of any object was only an apparent unity, it being really constituted of a multitude of interlaced and mutually related {77} particles, and all growth or increase of the object being conditioned by the introduction into the structure of additional atoms from without.
[149]
For the motions of the atoms he had no anterior cause to offer, other than necessity or fate. They existed, and necessarily and always had existed, in a state of whirl; and for that which always had been he maintained that no preceding cause could legitimately or reasonably be demanded.
[150]