Plato and the Other Companions of Sokrates, 3rd ed. Volume 1

The bridge, broken down by Parmenides, between the real and the phenomenal world, was thus in theory re-established. For the real world, as described by Demokritus, differed entirely from the sameness and barrenness of the Parmenidean Ens, and presented sufficient movement and variety to supply a basis of explanatory hypothesis, accommodated to more or less of the varieties in the phenomenal world. In respect of quality, indeed, all the atoms were alike, not less than all the vacua: such likeness was (according to Demokritus) the condition of their being able to act upon each other, or to combine as phenomenal aggregates.205 But in respect to quantity or magnitude as well as in respect to figure, they differed very greatly: moreover, besides all these diversities, the ordination and position of each atom with regard to the rest were variable in every way. As all objects of sense were atomic compounds, so, from such fundamental differences — partly in the constituent atoms themselves, partly in the manner of their arrangement when thrown into combination — arose all the diverse qualities and manifestations of the compounds. When atoms passed into new combination, then there was generation of a new substance: when they passed out of an old combination there was destruction: when the atoms remained the same, but were merely arranged anew in order and relative position, then the phenomenon was simply change.

Hence all qualities and manifestations of such compounds were not original, but derivative: they had no “nature of their own,” or law peculiar to them, but followed from the atomic composition of the body to which they belonged. They were not real and absolute, like the magnitude and figure of the constituent atoms, but phenomenal and relative — i.e. they were powers of acting upon correlative organs of sentient beings, and nullities in the absence of such organs.206 Such were the colour, sonorousness, taste, smell, heat, cold, &c., of the bodies around us: they were relative, implying correlative percipients. Moreover they were not merely relative, but perpetually fluctuating; since the compounds were frequently changing either in arrangement or in diversity of atoms, and every such atomic change, even to a small extent, caused it to work differently upon our organs.207

Among the various properties of bodies, however, there were two which Demokritus recognised as not merely relative to the observer, but also as absolute and belonging to the body in itself. These were weight and hardness — primary qualities (to use the phraseology of Locke and Reid), as contrasted with the secondary qualities of colour, taste, and the like. Weight, or tendency downward, belonged (according to Demokritus) to each individual atom separately, in proportion to its magnitude: the specific gravity of all atoms was supposed to be equal. In compound bodies one body was heavier than another, in proportion as its bulk was more filled with atoms and less with vacant space.208 The hardness and softness of bodies Demokritus explained by the peculiar size and peculiar junction of their component atoms. Thus, comparing lead with iron, the former is heavier and softer, the latter is lighter and harder. Bulk for bulk, the lead contained a larger proportion of solid, and a smaller proportion of interstices, than the iron: hence it was heavier. But its structure was equable throughout; it had a greater multitude of minute atoms diffused through its bulk, equally close to and coherent with each other on every side, but not more close and coherent on one side than on another.

The structure of the iron, on the contrary, was unequal and irregular, including larger spaces of vacuum in one part, and closer approach of its atoms in other parts: moreover these atoms were in themselves larger, hence there was a greater force of cohesion between them on one particular side, rendering the whole mass harder and more unyielding than the lead.209

We thus see that Demokritus, though he supposed single atoms to be all of the same specific gravity, yet recognised a different specific gravity in the various compounds of atoms or material masses. It is to be remembered that, when we speak of contact or combination of atoms, this is not to be understood literally and absolutely, but only in a phenomenal and relative sense; as an approximation, more or less close, but always sufficiently close to form an atomic combination which our senses apprehended as one object. Still every atom was essentially separate from every other, and surrounded by a margin of vacant space: no two atoms could merge into one, any more than one atom could be divided into two.

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.

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 own211 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.

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