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.
There is a distinction here, it will be observed, which at once
suggests the modern distinction between physical processes and
chemical processes, or, putting it otherwise, between molecular
processes and atomic processes; but the reader must be guarded
against supposing that Anaxagoras had any such thought as this in
mind. His ultimate mixable particles can be compared only with
the Daltonian atom, not with the molecule of the modern
physicist, and his "infinite, self- powerful, and unmixable"
particles are not comparable with anything but the ether of the
modern physicist, with which hypothetical substance they have
many points of resemblance. But the "infinite, self- powerful,
and unmixed" particles constituting thus an ether-like plenum
which permeates all material structures, have also, in the mind
of Anaxagoras, a function which carries them perhaps a stage
beyond the province of the modern ether. For these "infinite,
self powerful, and unmixed" particles are imbued with, and,
indeed, themselves constitute, what Anaxagoras terms nous, a word
which the modern translator has usually paraphrased as "mind."
Neither that word nor any other available one probably conveys an
accurate idea of what Anaxagoras meant to imply by the word nous.
For him the word meant not merely "mind" in the sense of
receptive and comprehending intelligence, but directive and
creative intelligence as well. Again let Anaxagoras speak for
himself: "Other things include a portion of everything, but nous
is infinite, and self-powerful, and mixed with nothing, but it
exists alone, itself by itself. For if it were not by itself, but
were mixed with anything else, it would include parts of all
things, if it were mixed with anything; for a portion of