1. The later philosophers of nature substituted for the dynamical principle, which had been invoked to explain the origin of the physical world, a principle of the mechanical order. The hylozoism of the earlier philosophers entirely disappeared. But though some of the later philosophers contented themselves with a mere cosmical mechanism, others postulated, besides this, a higher co-operating cause, and this admission of a dual principle in their cosmogony indicates an important advance in philosophic thought.
2. Amongst the later philosophers of nature are to be reckoned Empedocles of Agrigentum, Leucippus and Democritus of Abdera, and Anaxagoras of Clazomenae, with whom also we must connect Arcesilaus.
§ 14.
1. Empedocles was born at Agrigentum (about the year B.C. 500). His family belonged to the democratic party in the state, and for this party Empedocles, like his father, Meton, exerted himself successfully. He wandered through the Greek cities of Sicily and Italy in the several characters of physician, priest, orator, and worker of miracles. He proclaimed himself possessed of magical powers. Of his writings we know the names of only two, which can, with certainty, be ascribed to him, peri phuseôs and katharmoi (Diog. Laert. 7, 77). Fragments of the first of these are still preserved.
2. Empedocles did not, like the older Ionians, assume a single primal matter from which all things are produced. According to him all things come from a mingling of the four elements, earth, water, air, and fire. This mingling or mixture he views in the light of the causa materialis of all things in nature. He does not explain the origin and dissolution of things by a process of condensation and rarefaction such as was adopted by the older Ionians. His process is purely mechanical -- a mere separation and subsequent commingling of the primary elements or "Radical Principles" of all things. To account adequately for this separation and commingling, he assumes, in addition to the causa materialis already described, two active forces which he names, in symbolical language, Love and Hatred (philotês kai neikos). Hate he makes the dissociating separating principle; Love the principle of mixture and of union.
3. This being premised, he explains as follows the origin of the world: --
(a.) At first the four elements all mixed together formed a great globe or Sphairos (eudaimonestatos Theos, Arist. Met. 3.) which held all things within itself, in which Love was predominant and Hate without power. But Hate forced its way from the periphery to the centre of the Sphairos, it gained the mastery over Love; the elements were sundered and stood apart in separate existence.
(b.) It is clear that the undisputed supremacy of Hate would have entailed absolute separation of the elements which would have rendered it impossible for individual objects to come into being. But in the process of the world's formation Love strove against Hate and succeeded in uniting again the elements which had been separated. And so the several objects in this world were brought into existence.
(c.) It thus appears that the world can exist only as long as equilibrium is preserved between the rival cosmical forces. In the end, however, Love will gain the upper hand, the individual objects in the world will lose their individuality, and return to their first union. But at this stage Hate will again rise in its might to bring about the formation of another world -- and so on through endless periodic changes. Of the whole cycle of changes Necessity is the only law.
4. The first outcome of the formative process above described is Heaven with its luminous bodies, the formation of which is followed by that of the earth, and finally by that of the animal kingdom. "Amongst organic beings, plants first germinated from the earth while it was yet in process of formation; animals followed, but their several parts were first separately formed and then united by Love. There have been beings which were all eyes, others which were all arms, and so forth; from the union of these resulted many monsters which perished. But there also resulted some other organisms fitted to live, and these maintained themselves in existence and propagated their kind" (Arist. de coelo, 3. 2). "The influence of distant bodies upon one another as well as the possibility of mixture, Empedocles explains by admitting effluences (aporroai) from all things, and pores (por i) into which these effluences enter." All things are animated.
5. The human soul, like other things, is a mixture of the four elements, with Love and Hate as moving forces. For as like alone knows like, it follows that the soul, which knows all the elements, must contain within its own being the "radical principles" of all things -- the four elements -- otherwise, not resembling them in nature, it could possess no knowledge of them. Perception by the senses is explained by the theory of "effluences" already described, In the act of vision, e.g., two currents flow in different directions, there is an efflux from the visible objects to the eye, and an efflux through the pores of the eye of the internal elements, fire and water, and in the encounter of these currents the sense-image is generated. In analogous fashion the perceptions of the other senses are effected (Arist. de sensu, c., 2, 4. Theophr. de sensu, 9.) Empedocles ascribed Feeling and Desire to plants as well as to animals.
6. Empedocles describes the Deity as the self-satisfying, blissful Spirit. Its relation to the world is that of the One to the Many, of Love to Disunion. As a consequence of this view he frequently describes the cosmical force of unifying Love as God -- the two notions seem to be identified in his theory. "In the doctrine of Empedocles God knows Himself alone as Union and Love, the opposite He knows not at all. Having his being and habitation outside the sphere of strife he cannot be troubled by aught unlike himself, by life in contention, by evil, by the plurality and differences of things." Since like can alone know like, it follows that the soul can know God only on condition of its possessing, besides the four elements, some element of the divinity. This element is Reason.
7. The ethical principles involved in the teaching of Empedocles are no more than a tracing of the moral notions, Good and Evil, back to the contrast between the cosmical forces. "As in the physical order the individual comes forth by separation from the unity of the Sphairos, so in the moral order Evil is that which has fallen away from God, which has been separated from His friendship, and from harmony with His being." From this doctrine to the doctrine of Metempsychosis the transition was easy. "The souls that have fallen away from God are relegated to the earth where they pass through various corporeal forms till at last they are purged from Evil and return to the Divine Being again."