gone over in a different way. In common life it is quite possible to
use in the attainment of practical ends knowledge which has not been
analyzed and of the full meaning of which we are ignorant. I hope it
has become evident in the course of this volume that something closely
analogous is true in the field of science. The man of science may
measure space and time, and may study the phenomena of the human mind,
without even attempting to answer all the questions which may be raised
as to what is meant, in the last analysis, by such concepts as space,
time, and the mind.

That such concepts should be analyzed has, I hope, been made clear, if
only that erroneous and misleading notions as to these things should be
avoided. But when a man with a genius for metaphysical analysis
addresses himself to this task, he cannot simply hand the results
attained by his reflections over to his less reflective fellow-man.
His words are not understood; he seems to be dealing with shadows, with
unrealities; he has passed from the real world of common thought into
another world which appears to have little relation to the former.

Nor can verification, indubitable proof, be demanded and furnished as
it can in many parts of the field cultivated by the special sciences.
We may judge science fairly well without ourselves being scientists,
but it is not possible to judge philosophy without being to some extent
a philosopher.

In other words, the conclusions of reflective thought must be judged by
following the process and discovering its cogency or the reverse.
Thus, when the philosopher lays before us an argument to prove that we
must regard the only ultimate reality in the world as unknowable, and
must abandon our theistic convictions, how shall we make a decision as