EPICURUS B.C.), Greek philosopher, was born in Samos, where his father, Neocles, an Athenian, had settled some ten years before. In 323 he came to Athens, but shortly after joined his father in Colophon (Diog. Laert., x. I). Thereafter he taught in Mytilene and Lampsacus and in 3o6 returned to Athens, where he founded a school and established his permanent home. He taught and lived with his pupils near the Dipylon in a garden (Krtiros, Diog. Laert., x. 17, Epicuri hortus, Cic. N.D. i. 33; hence Cic. N.D. 43 Democritus . . . from whose waters Epicurus irrigated his gardens) which at his death he bequeathed to his school (cf. his will in Diog. Laert., x. 27). The society which he gathered round him included women as well as men, a circum stance which occasioned some scandalous legends. A more pleas ant story is told of his unsurpassed kindness to all, as testified by his country and his friends (Diog. Laert., x. 9), and of the sim plicity which characterized the regimen of his school (Diog. Laert. x. II).
The philosophic outlook of Epicurus is fundamentally ethical and his interest in other studies seems to have been small (cf. Diog. Laert., x. 2; 6; 31.). Even his interest in physics is purely subsidiary to the ethical end, i.e., to obtaining a theory of life which shall ensure "quietude of mind and a steadfast faith" (arapasLav Kai rio'TCV 0Ef3acov Diog. Laert., x. 85). According to Diog. Laert., x. 29 his philosophy is divided into three parts: canonical, physical, ethical; the first, dealing with "approaches (i 6hovs) to the study," i.e., with criteria of validity, being usually coupled with the physical.
Physics.—We are told by Diog. Laert., x. 2, that it was from the writings of Democritus that Epicurus received his first im pulse to philosophy. Be that as it may, the doctrine of Democritus regarding the atoms and the void is the basis of the teaching of Epicurus.
Nothing is created out of nothing and nothing passes into nothing. The universe (TO ray) was always such as it is now and always will be such, since there is nothing beyond the universe the entrance of which could effect a change. The universe consists of bodies (o ., aTa) and space the void). The existence of bodies is testified by sense (aioOsacs) and the exist ence of space is a necessary inference of reason ; for, if the void did not exist, bodies could not move as, in fact, sense assures us that they do move. Besides these two—bodies and space—nothing can even be imagined. Again, bodies are either compound or the elements of which bodies are compounded. These elements are indivisible (aro,ua, atoms) and unchange able; for, when a compound is resolved into its elements, the elements must either pass into nothingness—which we held to be impossible—or remain as ultimate indissoluble entities. Again the universe is infinite ; for the finite has an extremity (aKpov) which can only be observed against something else, which is ex hypothesi impossible in the case of the universe. Having, then, no ex tremity it has no limit (7rEpas) . Also the number of atoms and the extent of the void are infinite ; for if there were a limited number of atoms in unlimited void, the atoms could not remain anywhere but would drift, scattered through infinite void, not having atoms to support and place them by their collisions (avaKoirai Diog. Laert., x. 42). If on the other hand the void were limited and the atoms unlimited, there would not be room for them.
The atoms are not all of one shape (r i ua). The number of atoms of any one shape is absolutely infinite (a7rXt.s airapoc), but the number of different shapes, though incomprehensibly large, is not absolutely infinite (ovx a7rXc&s acre. pot aXAa /,covov airepLArlirroc).
The atoms vary in size but are not of all sizes : otherwise some would be visible. Whatever their size, they are in perpetual mo tion, moving all with the same velocity, swift as thought (aµa voiLuarc Diog. Laert., x. 61). Owing to an inherent "swerve" clinamen, Lucret., ii. 292—this, of course, is a necessary postulate, Lucret., ii. 243 Quare etiam atque etiam paulum inclinare necesse est Corpora. Plut. Mor. 964 C o1)6 yap avroc TW EirLKovpcp lu5haacv . . . aro sov irap€yKAcvac µiav TovX aXcarov) the atoms collide and rebound to a lesser or greater distance, thus forming compound bodies of greater or lesser density.
Psychology.—(i) The soul is a material body of fine parts (aW,ua AE7rroµepfs) and is distributed through the whole bodily structure. Compound bodies are of two sorts—those which are capable of holding together of themselves and those which can not do so unless protected (arEyaSo,ts€Va) by some more solid body. The soul belongs to the latter sort. So long as it is pro tected by the body, it is capable of sensation and of communi cating sensation to the body. When it leaves the body, it is dis sipated; the body, on the other hand, is no longer capable of sensation. (2) Sense-perception is a purely material process. From the surface of all bodies there are continually being dis charged images (E'iOWAa Diog. Laert., x. 46, simulacra Lucret., iv. 99, imagines Lucret., iv. 1oi ), hollow films (Diog. Laert., l.c. KocAwµaTa) of exceedingly fine texture, which in shape are an exact replica of the body (T zoc oµoaxibuoves rois arEpE,uviocs Diog. l.c.). These, reaching the soul through the various organs of sense, originate sensation. (3) Sensation is the sole source of knowledge and all sensuous perceptions are true. Error can arise only when, beyond what is given in sensation, the mind forms an opinion which is afterwards contradicted or unconfirmed (Diog. Laert., x. 5o. cf. ibid. 32; 146 f.).
According to Diog. Laert., x. 31 "In the Canon Epicurus says that the criteria of truth are the sensations (aioOila€ts) and con cepts (7rpoX iitkECs) and the feelings" (ir6.t77) ; the Epicureans add "the imaginative apprehensions of the mind" (Tas oavraarLKas 7rc/3oXas Tis btavoias). This passage, which should be compared with several passages in the Letter to Herodotus (Diog. Laert., x. 38; 50; 51 ; 62) and with K. A. xxiv. (Diog. Laert., x. raises some difficulties. By sensations is meant that which is immediately given by the senses. By concepts is meant the gen eral notion (notities, Lucret., v. 182 ; anticipatio sive praenotio, Cic. N.D. i. 17.43) formed by repeated sense-perceptions: Diog. Laert., x. 33 rip ai irpoXj 1'u1 AEyovvcv . . . KaBoXLKov vortarcv EVa7roica,ubtriV, rovrio TC /d.Vi//.6riv TOO 7rOAA6,KLr EEWBEV qSavEVTos, cf. ibid. 31; 72; 152 f., and especially 124, where we are told that "the assertions of the many about the gods are not conceptions (irpOArltkEts) but false suppositions (iiroXi 1'ECS 1bEvOEIc)." By the retention of these in the mind we are able, not merely to perceive an individual object as such, but to refer it to the general name. By feelings are meant apparently the "emotions," or, so to say, passive effects on the mind. Lastly the Oavraarucii Trls 8cavoias seems best referred to the power of the mind to form mental images (4)ays aaLac) intuitively. It would thus be equiva lent to the by which the gods are known (Letter to Menoeceus, 123) . The best commentary on the whole matter is K. A. xxiv. (Diog. Laert., x. 147), "If you reject any sensa tion absolutely and do not distinguish opinion in regard to that which awaits confirmation (TO bo a5 ayevov Kara TO 7rpoa/EVov from that which is already given (TO 'irapov) by sensation and feel ings and every imaginative apprehension of the mind, you will confound all other sensations as well and so reject every criterion." Ethics.—The criterion of good and evil is sensation : ray aya©Ov Kai KaKOV iv aiaOrioaa (Letter to Menoec., 124). Hence "we de clare pleasure to be the beginning and end of the blessed life ; for we recognize this to be our first and natural good, and from this we start in every choice and avoidance and this we make our goal, using feeling as the canon by which we judge every good" (ibid. 129). "But while every pleasure is in itself good, not all pleasures are to be chosen, since certain pleasures are produced by means which entail annoyances many times greater than the pleasures (K. A. viii.) . Moreover, a right conception of pleasure itself conduces to right living, since it is not possible to live pleasantly without living wisely and well and righteously" (K. A. v.). In this light the declaration that "beauty, virtue, and the like are to be valued if they produce pleasure ; if not, we must bid them farewell" (op. Athen. S46 f.) is not so hedonistic as it sounds. Pleasure as contemplated by Epicurus is not so much active enjoyment as the absence of pain: Diog. Laert., x. 136 "Epicurus differs from the Cyrenaics as regards Pleasure; for they do not admit static (KaraarriparLKriv) but only active (Trio KCY11aeL) Pleasure . . . But Epicurus in his work on Choice says : Quiet of mind (arapaLa) and absence of (bodily) pain (airovia) are static pleasures, but joy and mirth are seen in ac tivity" (cf. Plut. Mor. 1)).
The Gods.—Since happiness lies in quiet of mind (arapaEia Diog. Laert., x. 82 ; 85 ; 128 "all choice and avoidance are to be referred to health of body and quiet of mind, since this is the end of the blessed life") Epicurus is concerned to remove the two great disturbing ideas in human life—the fear of the gods and the fear of death (Letter to Herod, 81) . He does not deny the existence of the gods—"their existence is known to us by im mediate apprehension" (Letter to Menoec. 123, Oeoi yap duly ivapyris yap avrWV E(TTCV ri yvWacs.) : only they are not such as is vulgarly supposed. Fashioned of finer stuff than we, they dwell afar in the intermundial spaces (p€raKOapea Plut. Mor. 731 D, 734 C, intermundia Cic. N.D. i. 8. The lucid interspace of world and world, Tennyson, Lucretius), neither troubling nor troubled by the affairs of humanity, neither rewarding virtue nor punishing sin in this life. And, as we have seen above, there is no life to come, since the soul is of such a nature that, when it leaves the body, it is immediately dissolved into the primordial atoms of which it was compounded.