ation means the
reduction of millions of facts to one principle. But science does not
stop here. It seeks further to explain the laws themselves, and its
method is to reduce the many laws to one higher and more general law.
A familiar example of this is the explanation of Kepler's laws of the
planetary motions. Kepler laid down three such laws. The first was
that planets move in elliptical orbits with the sun in one focus. The
second was that planets describe equal areas in equal times. The third
was a rather more complicated law. Kepler knew these laws from
observation, but he could not explain them. They were explained by
Newton's discovery of the law of gravitation. Newton proved that
Kepler's three laws could be mathematically deduced from the law of
gravitation. In that way Kepler's laws were explained, 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. Obviously the ultimate goal would
be the explanation of all things by one principle. I do not mean to
say that scientific 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 ultimate 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 reason 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
explain all the other things in the world. It must be possible to
deduce the whole world from it. Secondly, the first principle must