Besides general notions we seem to find in the Timaeus some more
precise approximations to the discoveries of modern physical
science. First, the doctrine of equipoise. Plato affirms, almost
in so many words, that nature abhors a vacuum. Whenever a
particle is displaced, the rest push and thrust one another until
equality is restored. We must remember that these ideas were not
derived from any definite experiment, but were the original
reflections of man, fresh from the first observation of nature.
The latest word of modern philosophy is continuity and
development, but to Plato this is the beginning and foundation of
science; there is nothing that he is so strongly persuaded of as
that the world is one, and that all the various existences which
are contained in it are only the transformations of the same soul
of the world acting on the same matter. He would have readily
admitted that out of the protoplasm all things were formed by the
gradual process of creation; but he would have insisted that mind
and intelligence—not meaning by this, however, a conscious mind
or person—were prior to them, and could alone have created them.
Into the workings of this eternal mind or intelligence he does
not enter further; nor would there have been any use in
attempting to investigate the things which no eye has seen nor
any human language can express.
Lastly, there remain two points in which he seems to touch great
discoveries of modern times—the law of gravitation, and the
circulation of the blood.
(1) The law of gravitation, according to Plato, is a law, not
only of the attraction of lesser bodies to larger ones, but of
similar bodies to similar, having a magnetic power as well as a
principle of gravitation. He observed that earth, water, and air
had settled down to their places, and he imagined fire or the
exterior aether to have a place beyond air. When air seemed to go
upwards and fire to pierce through air—when water and earth fell
downward, they were seeking their native elements. He did not
remark that his own explanation did not suit all phenomena; and
the simpler explanation, which assigns to bodies degrees of
heaviness and lightness proportioned to the mass and distance of
the bodies which attract them, never occurred to him. Yet the
affinities of similar substances have some effect upon the
composition of the world, and of this Plato may be thought to
have had an anticipation. He may be described as confusing the
attraction of gravitation with the attraction of cohesion. The
influence of such affinities and the chemical action of one body
upon another in long periods of time have become a recognized
principle of geology.