1. Its Propounders.—Empedocles had sought to effect a combination of the Eleatic and Heraclitic principle—the same was attempted, though in a different way, by the Atomists, Leucippus and Democritus. Democritus, the better known of the two, was the son of rich parents, and was born about 460 B. C. in Abdera, an Ionian colony. He travelled extensively, and no Greek before the time of Aristotle possessed such varied attainments. He embodied the wealth of his collected knowledge in a series of writings, of which, however, only a few fragments have come down to us. For rhythm and elegance of language, Cicero compared him with Plato. He died in a good old age.

2. The Atoms.—Empedocles derived all determinateness of the phenomenal from a certain number of qualitatively determined and undistinguishable original materials, while the Atomists derived the same from an originally unlimited number of constituent elements, or atoms, which were homogeneous in respect of quality, but diverse in respect of form. These atoms are unchangeable, material particles, possessing indeed extension, but yet indivisible, and can only be determined in respect of magnitude. As being, and without quality, they are entirely incapable of any transformation or qualitative change, and, therefore, all becoming is, as with Empedocles, only a change of place. The manifoldness of the phenomenal world is only to be explained from the different form, disposition, and arrangement of the atoms as they become, in various ways, united.

3. The Fulness and the Void.—The atoms, in order to be atoms, i. e. undivided and impenetrable unities,—must be mutually limited and separated. There must be something set over against them which preserves them as atoms, and which is the original cause of their separateness and impenetrability. This is the void space, or more strictly the intervals which are found between the atoms, and which hinder their mutual contact. The atoms, as being and absolute fulness, and the interval between them, as the void and the not-being, are two determinations which only represent in a real and objective way, what are in thought, as logical conceptions, the two elements in the Heraclitic becoming, viz. being and the not-being. But since the void space is one determination of being, it must possess objective reality no less than the atoms, and Democritus even went so far as to expressly affirm in opposition to the Eleatics, that being is no more than nothing.

4. The Atomistic Necessity.—Democritus, like Empedocles, though far more extensively than he, attempted to answer the question—whence arise these changes and movements which we behold? Wherein lies the ground that the atoms should enter into these manifold combinations, and bring forth such a wealth of inorganic and organic forms? Democritus attempted to solve the problem by affirming that the ground of movement lay in the gravity or original condition of the material particles, and, therefore, in the matter itself, but in this way he only talked about the question without answering it. The idea of an infinite series of causalities was thus attained, but not a final ground of all the manifestations of the becoming, and of change. Such a final ground was still to be sought, and as Democritus expressly declared that it could not lie in an ultimate reason ????, where Anaxagoras placed it, there only remained for him to find it in an absolute necessity, or a necessary pre-determinateness ??????. This he adopted as his “final ground,” and is said to have named it chance t???, in opposition to the inquiry after final causes, or the Anaxagorean teleology. Consequent upon this, we find as the prominent characteristic of the later Atomistic school (Diagoras the Melier), polemics against the gods of the people, and a constantly more publicly affirmed Atheism and Materialism.

5. Relative Position of the Atomistic Philosophy.—Hegel characterizes the relative position of the Atomistic Philosophy as follows, viz.:—“In the Eleatic Philosophy being and not-being stand as antitheses,—being alone is, and not-being is not; in the Heraclitic idea, being and not-being are the same,—both together, i. e. the becoming, are the predicate of concrete being; but being and not-being, as objectively determined, or in other words, as appearing to the sensuous intuition, are precisely the same as the antithesis of the fulness and the void. Parmenides, Heraclitus and the Atomists all sought for the abstract universal; Parmenides found it in being, Heraclitus in the process of being per se, and the Atomists in the determination of being per se.” So much of this as ascribes to the Atomists the characteristic predicate of being per se is doubtless correct,—but the real thought of the Atomistic system is rather analogous with the Empedoclean, to explain the possibility of the becoming, by presupposing these substances as possessing being per se, but without quality. To this end the not-being or the void, i. e. the side which is opposed to the Eleatic principle, is elaborated with no less care than the side which harmonizes with it, i. e. that the atoms are without quality and never change in their original elements. The Atomistic Philosophy is therefore a mediation between the Eleatic and the Heraclitic principles. It is Eleatic in affirming the undivided being per se of the atoms;—Heraclitic, in declaring their multeity and manifoldness. It is Eleatic in the declaration of an absolute fulness in the atoms, and Heraclitic in the claim of a real not-being, i. e. the void space. It is Eleatic in its denial of the becoming, i. e. of the arising and departing,—and Heraclitic in its affirmation that to the atoms belong movement and a capacity for unlimited combinations. The Atomists carried out their leading thought more logically than Empedocles, and we might even say that their system is the perfection of a purely mechanical explanation of nature, since all subsequent Atomists, even to our own day, have only repeated their fundamental conceptions. But the great defect which cleaves to every Atomistic system, Aristotle has justly recognized, when he shows that it is a contradiction, on the one hand, to set up something corporeal or space-filling as indivisible, and on the other, to derive the extended from that which has no extension, and that the consciousless and inconceivable necessity of Democritus is especially defective, in that it totally banishes from nature all conception of design. This is the point to which Anaxagoras turns his attention, and introduces his principle of an intelligence working with design.