which we are rightly said to walk not by sight but by faith.

Now, before going on to say anything more about the message thus given
to us from the spiritual world, it is necessary to consider an objection
that meets us on the threshold of all such doctrines, namely, that it is
simply impossible for us to know anything whatever of things in
themselves. Our knowledge, it is urged, is necessarily relative to
ourselves, whereas absolute as distinct from relative knowledge is for
ever beyond our reach. We can speak of what things appear to us to be;
we cannot speak of what they are. We know or may know whatever comes
under the observation of our senses as phenomena; we cannot know what
underlies these phenomena. And sometimes it has been maintained that we
not only cannot know what it is that underlies the phenomena, but cannot
even know whether anything at all underlies the phenomena, and that, for
aught we can tell, the whole world and all that exists or happens in it
may be nothing but a system of appearances with no substance whatever.
This doctrine of the relativity of all knowledge is not only applied to
things external but to our very selves. We know ourselves, it is
maintained, only through an internal sense which can only tell us how we
appear to ourselves, but cannot tell us in any the least degree what we
really are.

Now this contention is an instance of a tendency against which we are
required to be perpetually on our guard. The final aim of all science
and of all philosophy is to find some unity or unities that shall
co-ordinate the immense complexity of the world in which we live. Now
there is one and only one legitimate way of attaining this aim, and that
is by patient, persevering study of the facts. But the facts turn out to
be so numerous, so multifarious, that not one life nor one generation
but many lives and many generations will assuredly not co-ordinate them