Epicurus divided the whole field of knowledge into three parts, to which he gave the names respectively of canonics," physics,' and ethics.' The first two were subordinate to the third. The end of all knowledge, of ethics directly or immediately, of canonics and physics indirectly or mediately through ethics, was, according to Epicurus, to increase the happiness of man.
Canonics, which was a subject altogether introductory both to physics and ethics, treated of the means by which knowledge, both physical and ethical, was obtained, and of the conditions or (as they were called by Epicurus) 'criteria' of truth. These conditions or criteria were, according to him, sensations (alaVicrets), ideas or imaginations (lyo aiEcs), and affections (arciOn). From these three sorts of consciousness we get all our knowledge. What Epicurus then called canonics, viewed in relation to physics and ethics, is, viewed absolutely or in itself, psychology. Epicurus seems to have explained rightly the depend ence of ideas upon sensations (Diog. Laert., x. 33); but in accounting for Peculation:3, he, like Democritus, left the path of sound psychology, and introduced the fanciful hypothesis of emanations from bodies.
In physics he trod pretty closely in the footsteps of Democritus [Ds:smarms]; so much so that he was accused of taking his atomic cosmology from that philosopher without acknowledgment : he made indeed very few and unimportant alterations. According to Epicurus, as also to Democritus and Leucippus before him, the universe consists of two parts, matter and space, or vacuum, in which matter exists and moves ; and all matter, of every kind and form, is reducible to certain indivisible particles, atoms, which are eternal. These atoms, moving, according to a natural tendency, straight downwards, and also obliquely, have thereby come to form the different bodies which are found in the world, and which differ, in kind and shape, according as the atoms aro differently placed in respect of one another. It ie clear that in this system a creator is dispensed with ; and indeed Epicurus, hero again following Democritns, set about to prove, In an la priori way, that this creator could not exist, inasmuch as nothing could arise out of nothing, any more than it could utterly perish and become nothing.
The atoms have existed always, and always will exist; and all the various physical phenomena are brought about, from time to time, by their various motions.
It remains to speak of the Epicurean system of ethics. Setting out from the two facts, that man is susceptible of pleasure and pain, and that he seeks the one and avoids the other, Epicurus propounded that it is a man's duty to endeavour to increase to the utmost his pleasures and. diminish to the utmost his pains; choosing that which tends to pleasure rather than that which tends to pain, and that which tends to a greater pleasure or to a lesser pain, rather than that which tends respectively to a lesser pleasure or to a greater pain. He used the terms pleasure and pain in the most comprehensive way, as including pleasure and pain both of mind and of body ; and he esteemed the pleasures and pains of the mind as incomparably greater than those of the body. Making then good and evil, or virtue and vice, depend on a tendency to increase diminish pain, or the opposite, he arrived, as he easily might do, at the several virtues to be inculcated and vices to he denounced. And when he got thus far, even his adver saries bad nothing to say against him. It is strange that they should
have continued to revile the principle, no matter by what name it might be called, when they saw that it was a principle that led to truth. But even in our own ago and country the same cry has been raised ; and men, ignorant of the principles of tho ancient and of the modern philosopher alike, have endeavoured, by bringing to bear on it as a hard name the name Epicurean, to crush the philosophy of Bentham.
Though Epicurus dispensed with a Diviue Being as creator of the world, he yet did net deny the existence of gods. That there was an inconsistency in this is obvious. But he professed that the universal prevalence of the ideas of gods was sufficient to prove that they existed; and thinking it necessary to derive these ideas, like all other ideas, from sensations, he imagined that the gods were beings of human form, hovering about in the air, and made known to men by the customary emanations. He believed that these gods were eternal and supremely happy, living in n state of quiet, and meddling not with the affairs of the world. He contended that they were to bo wor shipped on account of the excellence of their nature, not because they could do men either good or harm. (Cie., De Nat. Deor.,' i. 41; Senec., 'De Benef.,' iv. 19.) The two chief sources of knowledge concerning the doctrines of Epicurus are the tenth book of Diogenes Laertius, and the poem of Lucretius 'Do Reruns Nature.' In the first of these are letters from Epicurus himself to three of his friends, which give a brief account of all the parts of his system. information is furnished also by the writings of Cicero, principally the 'De Finibus' and the 'De Natur5, by those of Seneca; and the treatise of Plutarch, entitled ' Against Colotes.' Epicurus was, according to Diogenes Laertius, a more voluminous writer than any other philosopher, having written as mauy as 300 volumes, in all of which he is said to have studiously avoided making quotations. All that now remains of his works are the letters con tained in the tenth book of Diogenee Laertius, and parts of two books of his treatise on Nature Owl Orreen), which were discovered at Her culaneum. The last were published at Leipzig in 1818, being edited by Orelli. A critical edition of the first two lettere of Epicurus was edited by T. Glo. Schneider, Leipzig, 1813.
Diogenes I.:teal:3e is the principal authority for the life of Epicurus; brief and incidental notices are also supplied by Suidas, Cicero, Seneca, and Plutarch. Thero is an account of the life and defence of the character of Epicurus, in eight books, by Gassendi (Lugd. Bat., 1647), and a life by a Frenchman of the name of Rendal (Par., 1679). It is unnecessary to mention the accounts given in Fabricius, Bayle, and all the co.nmen histories of philosophy.
The Epicurean school was carried on, after Hermachus, by Poly stratus and many others, concerning whom nothing particular is known ; and the doctrines which Epicurus had taught underwent few modi fications. When introduced among the Romans, these doctrines, though very much opposed, were yet adopted by many distinguished men, as Lucretius, Atticus, Horace ; and under the emperors, Pliny the Younger and Lucian of Samosata were Epicureans. A list of Epicureans among the Greeks and Romans will be found in Fabricius, Bibliotheca Gratea,' ed. Harles., voL iii. pp. 598-614.