Anaxagoras found such an explanation, and, as good luck would have it, that explanation has been preserved. Let us examine his reasoning in some detail. We have already referred to the claim alleged to have been made by Anaxagoras that snow is not really white, but black. The philosopher explained his paradox, we are told, by asserting that snow is really water, and that water is dark, when viewed under proper conditions–as at the bottom of a well. That idea contains the germ of the Clazomenaean philosopher’s conception of the nature of matter. Indeed, it is not unlikely that this theory of matter grew out of his observation of the changing forms of water. He seems clearly to have grasped the idea that snow on the one hand, and vapor on the
other, are of the same intimate substance as the water from which they are derived and into which they may be again transformed.
The fact that steam and snow can be changed back into water, and by simple manipulation cannot be changed into any other substance, finds, as we now believe, its true explanation in the fact that the molecular structure, as we phrase it–that is to say, the ultimate particle of which water is composed, is not changed, and this is precisely the explanation which Anaxagoras gave of the same phenomena. For him the unit particle of water constituted an elementary body, uncreated, unchangeable, indestructible. This particle, in association with like particles, constitutes the substance which we call water. The same particle in association with particles unlike itself, might produce totally different substances–as, for example, when water is taken up by the roots of a plant and becomes, seemingly, a part of the substance of the plant. But whatever the changed association, so Anaxagoras reasoned, the ultimate particle of water remains a particle of water still. And what was true of water was true also, so he conceived, of every other substance.
Gold, silver, iron, earth, and the various vegetables and animal tissues–in short, each and every one of all the different substances with which experience makes us familiar, is made up of unit particles which maintain their integrity in whatever combination they may be associated. This implies, obviously, a multitude of primordial particles, each one having an individuality of its own; each one, like the particle of water already cited, uncreated, unchangeable, and indestructible.
Fortunately, we have the philosopher’s own words to guide us as to his speculations here. The fragments of his writings that have come down to us (chiefly through the quotations of Simplicius) deal almost exclusively with these ultimate conceptions of his imagination. In ascribing to him, then, this conception of diverse, uncreated, primordial elements, which can never be changed, but can only be mixed together to form substances of the material world, we are not reading back post-Daltonian knowledge into the system of Anaxagoras. Here are his words: “The Greeks do not rightly use the terms ‘coming into being’ and ‘perishing.’
For nothing comes into being, nor, yet, does anything perish; but there is mixture and separation of things that are. So they would do right in calling ‘coming into being’ ‘mixture’ and ‘perishing’
‘separation.’ For how could hair come from what is not hair? Or flesh from what is not flesh?”
Elsewhere he tells us that (at one stage of the world’s development) “the dense, the moist, the cold, the dark, collected there where now is earth; the rare, the warm, the dry, the bright, departed towards the further part of the aether. The earth is condensed out of these things that are separated, for water is separated from the clouds, and earth from the water; and from the earth stones are condensed by the cold, and these are separated farther from the water.” Here again the influence of heat and cold in determining physical qualities is kept pre-eminently in mind. The dense, the moist, the cold, the dark are contrasted with the rare, the warm, the dry, and bright; and the formation of stones is spoken of as a specific condensation due to the influence of cold. Here, then, we have nearly all the
elements of the Daltonian theory of atoms on the one hand, and the nebular hypothesis of Laplace on the other. But this is not quite all. In addition to such diverse elementary particles as those of gold, water, and the rest, Anaxagoras conceived a species of particles differing from all the others, not merely as they differ from one another, but constituting a class by themselves; particles infinitely smaller than the others; particles that are described as infinite, self-powerful, mixed with nothing, but existing alone. That is to say (interpreting the theory in the only way that seems plausible), these most minute particles do not mix with the other primordial particles to form material substances in the same way in which these mixed with one another. But, on the other hand, these “infinite, self-powerful, and unmixed” particles commingle everywhere and in every substance whatever with the mixed particles that go to make up the substances.