Pursuant to this theory, Demokritus proclaimed that all the properties of objects, except weight, hardness, and softness, were not inherent in the objects themselves, but simply phenomenal and relative to the observer — “modifications of our sensibility”. Colour, taste, smell, sweet and bitter, hot and cold, &c., were of this description. In respect to all of them, man differed from other animals, one man from another, and even the same man from himself at different times and ages. There was no sameness of impression, no unanimity or constancy of judgment, because there was no real or objective “nature” corresponding to the impression. From none of these senses could we at all learn what the external thing was in itself. “Sweet and bitter, hot and cold (he said) are by law or convention (i.e. these names designate the impressions of most men on most occasions, taking no account of dissentients): what really exists is, atoms and vacuum. The sensible objects which we suppose and believe to exist do not exist in truth; there exist only atoms and vacuum. We know nothing really and truly about an object, either what it is or what it is not: our opinions depend upon influences from without, upon the position of our body, upon the contact and resistances of external objects. There are two phases of knowledge, the obscure and the genuine. To the obscure belong all our senses — sight, hearing, smell, taste, touch. The genuine is distinct from these. When the obscure phase fails, when we can no longer see, nor hear, nor smell, nor taste, nor touch — from minuteness and subtlety of particles — then the genuine phase, or reason and intelligence, comes into operation.”[210]
[210] Demokritus, Fr. p. 205, Mullach; Sextus Empiric. adv. Mathemat. vii. p. 135; Diogen. Laert. ix. 72.
Reason alone gave true and real knowledge, but very little of it was attainable.
True knowledge (in the opinion of Demokritus) was hardly at all attainable; but in so far as it could be attained, we must seek it, not merely through the obscure and insufficient avenues of sense, but by reason or intelligence penetrating to the ultimatum of corpuscular structure, farther than sense could go. His atoms were not pure Abstracta (like Plato’s Ideas and geometrical plane figures, and Aristotle’s materia prima), but concrete bodies, each with its own[211] magnitude, figure, and movement; too small to be seen or felt by us, yet not too small to be seen or felt by beings endowed with finer sensitive power. They were abstractions mainly in so far as all other qualities were supposed absent. Demokritus professed to show how the movements, approximations, and collisions of these atoms, brought them into such combinations as to form the existing Kosmos; and not that system alone, but also many other cosmical systems, independent of and different from each other, which he supposed to exist.
[211] Aristotel. Gen. et Corr. i. 8, p. 325, a. 29. Ἄπειρα τὸ πλῆθος καὶ ἀόρατα διὰ σμικρότητα τῶν ὄγκων, &c.
Marbach observes justly that the Demokritean atoms, though not really objects of sense in consequence of their smallness (of their disproportion to our visual power), are yet spoken of as objects of sense: they are as it were microscopic objects, and the γνησίη γνώμη, or intelligence, is conceived as supplying something of a microscopic power. (Marbach, Lehrbuch der Geschichte der Philosophie, sect. 58, vol. i. p. 94.)
No separate force required to set the atoms in motion — they moved by an inherent force of their own. Like atoms naturally tend towards like. Rotatory motion, the capital fact of the Kosmos.
How this was done we cannot clearly make out, not having before us the original treatise of Demokritus, called the Great Diakosmos. It is certain, however, that he did not invoke any separate agency to set the atoms in motion — such as the Love and Discord of Empedokles — the Nous or Intelligence of Anaxagoras. Demokritus supposed that the atoms moved by an inherent force of their own: that this motion was as much without beginning as the atoms themselves:[212] that eternal motion was no less natural, no more required any special cause to account for it, than eternal rest. “Such is the course of nature — such is and always has been the fact,” was his ultimatum.[213] He farther maintained that all the motions of the atoms were necessary — that is, that they followed each other in a determinate order, each depending upon some one or more antecedents, according to fixed laws, which he could not explain.[214] Fixed laws, known or unknown, he recognised always. Fortune or chance was only a fiction imagined by men to cover their own want of knowledge and foresight.[215] Demokritus seems to have supposed that like atoms had a spontaneous tendency towards like; that all, when uncombined, tended naturally downwards, yet with unequal force, owing to their different size, and weight proportional to size; that this unequal force brought them into impact and collision one with another, out of which was generated a rotatory motion, gradually extending itself, and comprehending a larger and larger number of them, up to a certain point, when an exterior membrane or shell was formed around them.[216] This rotatory motion was the capital fact which both constituted the Kosmos, and maintained the severance of its central and peripheral masses — Earth and Water in the centre — Air, Fire, and the celestial bodies, near the circumference. Demokritus, Anaxagoras, and Empedokles, imagined different preliminary hypotheses to get at the fact of rotation; but all employed the fact, when arrived at, as a basis from which to deduce the formation of the various cosmical bodies and their known manifestations.[217] In respect to these bodies — Sun, Moon, Stars, Earth, &c. — Demokritus seems to have held several opinions like those of Anaxagoras. Both of them conceived the Sun as a redhot mass, and the Earth as a flat surface above and below, round horizontally like a drum, stationary in the centre of the revolving celestial bodies, and supported by the resistance of air beneath.[218]
[212] Aristotel. De Cœlo, iii. 2, 3, p. 300, b. 9. Λευκίππῳ καὶ Δήμοκριτῳ, τοῖς λέγουσιν ἀεὶ κινεῖσθαι, τὰ πρῶτα σώματα, &c. (Physic. viii. 3, 3, p. 253, b. 12, viii. 9, p. 265, b. 23; Cicero, De Finib. i. 6, 17.)
[213] Aristot. Generat. Animal. ii. 6, p. 742, b. 20; Physic. viii. 1, p. 252, b. 32.