Such reflections, although this is not the place in which to
dwell upon them at length, lead us to take a favourable view of
the speculations of the Timaeus. We should consider not how much
Plato actually knew, but how far he has contributed to the
general ideas of physics, or supplied the notions which, whether
true or false, have stimulated the minds of later generations in
the path of discovery. Some of them may seem old-fashioned, but
may nevertheless have had a great influence in promoting system
and assisting enquiry, while in others we hear the latest word of
physical or metaphysical philosophy. There is also an
intermediate class, in which Plato falls short of the truths of
modern science, though he is not wholly unacquainted with them.
(1) To the first class belongs the teleological theory of
creation. Whether all things in the world can be explained as the
result of natural laws, or whether we must not admit of
tendencies and marks of design also, has been a question much
disputed of late years. Even if all phenomena are the result of
natural forces, we must admit that there are many things in
heaven and earth which are as well expressed under the image of
mind or design as under any other. At any rate, the language of
Plato has been the language of natural theology down to our own
time, nor can any description of the world wholly dispense with
it. The notion of first and second or co-operative causes, which
originally appears in the Timaeus, has likewise survived to our
own day, and has been a great peace-maker between theology and
science. Plato also approaches very near to our doctrine of the
primary and secondary qualities of matter. (2) Another popular
notion which is found in the Timaeus, is the feebleness of the
human intellect—‘God knows the original qualities of things; man
can only hope to attain to probability.’ We speak in almost the
same words of human intelligence, but not in the same manner of
the uncertainty of our knowledge of nature. The reason is that
the latter is assured to us by experiment, and is not contrasted
with the certainty of ideal or mathematical knowledge. But the
ancient philosopher never experimented: in the Timaeus Plato
seems to have thought that there would be impiety in making the
attempt; he, for example, who tried experiments in colours would
‘forget the difference of the human and divine natures.’ Their
indefiniteness is probably the reason why he singles them out, as
especially incapable of being tested by experiment. (Compare the
saying of Anaxagoras—Sext. Pyrrh.—that since snow is made of
water and water is black, snow ought to be black.)