DEMOCRITUS, one of the founders of the Atomic philosophy, was born at Abdera, a Thracian colony, the inhabitants of which were notorious for their stupidity. Nearly all the information that we possess concerning his life consists of traditions of very doubtful authenticity. He was a contemporary of Socrates ; but the date of his birth has been fixed variously from 494 to 460 B.C. His father (who is called by no less than three names) was a man of such wealth as to be able to entertain Xerxes and his army on their return home after the battle of Salamis. On coming into his inheritance, Democritus, there is good reason to believe, devoted several years to travel. He visited the East, and is supposed with great probability to have spent a considerable time in Egypt. The intensity of his thinking was figured by the ancients in the story that he put out his eyes in order that he might not be diverted from his meditations. But of the way in which he obtained the vast learning for which he was famed, and of his inter-course with other philosophers, even with Leucippus, we have no certain information. According to one very doubtful tradition, he was so honoured in his native city that, his patrimony being all spent, the Incredible sum of 500 talents was voted him by his fellow-citizens, together with the honour of a public funeral ; but, according to another tradition, his countrymen regarded him as a lunatic and sent for Hippocrates to cure him. All are agreed that he lived to a great age ; Diodorus Siculu3 states that he was ninety at his death, and others assert that he was nearly twenty years older. He left, according to Diogenes Laertius, no less that 72 works, treating of almost every subject studied in his time, and written in Ionic Greek, in a style which for poetic beauty Cicero deemed worthy of comparison with that of Plato. But of
all these works nothing has come down to us beyond small fragments.
The cosmical theory propounded by Democritus.which in part at least was adopted from the doctrines of Leucippus is of all the materialistic explanations of the universe put forth by the Greeks the one which has held the most permanent place in philosophical thought. All that exists is vacuum and atoms. The atoms are the ultimate material of all things, including spirit. They are uncaused, and have existed from eternity. They are invisible, but extended, heavy, and impenetrable. They vary in shape ; though whether Democritus held that they vary also in density is debated. And, lastly, these atoms are in motion. This motion, like the atoms themselves, Democritus held to be eternal. According to some, he explained it as caused by the downward fall of the heavier atoms through the lighter, by which means a lateral whirling motion was pro-duced ; but whether this explanation was given by Democritus is extremely doubtful. Another principle also is said by some to have been used by Democritus to explain the concurrence of the atoms in certain ways, viz., that there is an innate necessity by which similar atoms come together. However this may be, he did declare that by the motion of the atoms the world was produced with all that it contains.
Soul and fire are of one nature ; the atoms of which they consist are small, smooth, and round; and it is by inhaling and exhaling such atoms that life is maintained. It follows that the soul perishes with, and in the same sense as, the body. There is, in fact, no distinction made be-tween the principle of life and the higher mental faculties.
The Atomic theory of perception was as follows. From every object eîSaAa. (or images) of the object are continually being given off in all directions ; these enter the organs of sense, and give rise to sensation. The rest of the theory remarkably anticipates certain famous modern theories of perception (1) by its reduction of all sensation, on the objective side, to touch, and (2) by the distinction which it involves between the qualities of extension and resistance, which are said to be the only qualities that really belong to objects of sense, and the other (or secondary) qualities, which are said to exist only through the action of the organs of sense modifying the eïSwÀa.
Sensation, Democritus appears to have taught, is our only source or faculty of knowledge ; indeed his first prin-ciples admit the existence of no mental faculty of a nature distinct from sensation. He was classed among the most extreme sceptics of antiquity, and tradition attributes to him such sayings as" There is nothing true, and if there is, we do not know it," "We know nothing, not even if there is anything to know."
Ttie system of Democritus was altogether anti-theological. He denied that the creation of the world was in any way due to reason. He also rejected all the popular mythology ; but, according to one account, he taught that, as men were produced by the motion of the atoms, so was produced a race of grander beings, of similar form, and, though longer-lived, still mortal, who influence human affairs, some benevolently, some malevolently, and who appear to men in dreams.
The moral system of Democritus is strikingly like the negative side of the system of Epicurus. The summum bonum is placed in an even tranquillity of mind. Fear, and too strong desire, and all that is likely to bring sorrow or even care, are to be avoided, as, for example, notably mar-riage, to which Democritus cherished the strongest objec-tions. This habit of mind Democritus is said to have himself so well attained that the merry spirit with which he re-garded all that happened earned him the title of " the laughing philosopher." Another version, however, asserts that he received the name on account of the scorn which he poured on human ignorance and weakness.
See Mullach, Democriti Abderitce operum fragmenta, Berlin, 1843; Franck, " Fragments qui subsistent de Démocrite," in the Mémoires de la Société royale de Nancy, 1836 ; Eitter, Geschichte der Philosophie, vol. i. ; Brandis, Rhein. Museum, vol. iii., and Geschichte der Griech und Rom Philosophie, vol. i. ; H. Stephanus, Poesis Philos. ; Burchardt, Commeniaria critica de Democriti de sensibus philosophia, 1839 ; and Fragmente der Moral des Democrit.