? Neither the philosophy of Locke, nor
that of Descartes, nor that of Kant, can be vindicated as can a
prediction touching an eclipse of the sun. To judge these men, we must
learn to think with them, to survey the road by which they travel; and
this we cannot do until we have learned the art.

Whether we like to admit it or not, we must admit, if we are
fair-minded and intelligent, that philosophy cannot speak with the same
authority as science, where science has been able to verify its
results. There are, of course, scientific hypotheses and speculations
which should be regarded as being quite as uncertain as anything
brought forward by the philosophers. But, admitting this, the fact
remains that there is a difference between the two fields as a whole,
and that the philosopher should learn not to speak with an assumption
of authority. No final philosophy has been attained, so palpably firm
in its foundation, and so admittedly trustworthy in its construction,
that we are justified in saying: Now we need never go back to the past
unless to gratify the historic interest. It is a weakness of young
men, and of older men of partisan temper, to feel very sure of matters
which, in the nature of things, must remain uncertain.

Since these things are so, and since men possess the power of
reflection in very varying degree, it is not surprising that we find it
worth while to turn back and study the thoughts of those who have had a
genius for reflection, even though they lived at a time when modern
science was awaiting its birth. Some things cannot be known until
other things are known; often there must be a vast collection of
individual facts before the generalizations of science can come into
being. But many of the problems with which reflective thought is still
struggling have not been furthered in the least by information which
has been collected during the centuries which have elapsed since they
were attacked by the early Greek philosophers.

Thus, we are still discussing the distinction between "appearance" and
"reality," and many and varied are the opinions at which philosophers
arrive. But Thales, who heads the list of the Greek philosophers, had
quite enough material, given in his own experience, to enable him to
solve this problem as well as any modern philosopher, had he been able
to use the material. He who is familiar with the history of philosophy
will recognize that, although one may smile at Augustine's