and not only Kepler’s laws, but many other astronomical
laws and facts. Thus the explanation of the many isolated
facts consists in their reduction to the one law, and the
explanation of the many laws consists in their reduction
to the one more general law. As knowledge advances, the
phenomena of the universe come to be explained by fewer
and fewer, and wider and wider, general principles. Ob-
viously the ultimate goal would be the explanation of all
things by one principle. I do not mean to say that scien-
tific men have this end consciously in view. But the point is
that the monistic tendency is there. What is meant by the
explanation is the reduction of all things to one principle.
{66}
In philosophy, in religion, and in science, then, we find this
monistic tendency of thought. But it might be asked how
we know that this universal tendency is right? How do
we know that it is not merely a universal error? Is there
no logical or philosophical basis for the belief that the ul-
timate explanation of things must be one? Now this is a
subject which takes us far afield from Greek philosophy.
The philosophical basis of monism was never thought out
till the time of Spinoza. So we cannot go into it at length
here. But, quite shortly, the question is—Is there any rea-
son for believing that the ultimate explanation of things
must be one? Now if we are to explain the universe, two
conditions must be fulfilled. In the first place, the ultimate
reality by which we attempt to explain everything must ex-
plain all the other things in the world. It must be possible
to deduce the whole world from it. Secondly, the first prin-
ciple must explain itself. It cannot be a principle which
itself still requires explanation by something else. If it is
itself not self-explanatory, but is an ultimate mystery, then
even if we succeed in deducing the universe from it, noth-
ing is thereby explained. This, for example, is precisely the
defect of materialism. Even if we suppose it proved that
all things, including mind, arise from matter, yet the ob-
jection remains that this explains nothing at all, for matter
is not a self-explanatory existence. It is an unintelligible
mystery. And to reduce the universe to an ultimate mys-
tery is not to explain it. Again; some people think that the
world is to be explained by what they call a “first cause.”
But why should any cause be the first? Why should we
stop anywhere in the chain of causes? Every cause is {67}
necessarily the effect of a prior cause. The child, who is
told that God made the world, and who inquires who, in
that case, made God, is asking a highly sensible question.
Or suppose, in tracing back the chain of causes, we come
upon one which we have reason to say is really the first, is
anything explained thereby? Still we are left with an ul-
timate mystery. Whatever the principle of explanation is,
it cannot be a principle of this kind. It must be a princi-
ple which explains itself, and does not lead to something
further, such as another cause. In other words, it must be
a principle which has its whole being in itself, which does
not for its completeness refer us to anything beyond itself.
It must be something fully comprehended in itself, without
reference to anything outside it. That is to say, it must
be what we call self-determined or absolute. Now any ab-
solute principle must necessarily be one. Suppose that it
were two. Suppose you attempt to explain the world by
two principles, X and Y, each of which is ultimate, neither