What are space and time? What is the mind? How are mind and body
related? How do we know that there are other minds than ours? etc.
These have been presented as _philosophical_ problems; and when we turn
back to the history of speculative thought we find that they are just
the problems with which the men whom we agree to call philosophers have
chiefly occupied themselves.

But when we turn to our treatises on _metaphysics_, we also find that
these are the problems there discussed. Such treatises differ much
among themselves, and the problems are not presented in the same form
or in the same order; but one who can look beneath the surface will
find that the authors are busied with much the same thing--with some or
all of the problems above mentioned.

How, then, does metaphysics differ from philosophy? The difference
becomes clear to us when we realize that the word philosophy has a
broader and looser signification, and that metaphysics is, so to speak,
the core, the citadel, of philosophy.

We have seen (Chapter II) that the world and the mind, as they seem to
be presented in the experience of the plain man, do not stand forth
with such clearness and distinctness that he is able to answer
intelligently the questions we wish to ask him regarding their nature.
It is not merely that his information is limited; it is vague and
indefinite as well. And we have seen, too, that, however the special
sciences may increase and systematize his information, they do not
clear away such vagueness. The man still uses such concepts as "inner"
and "outer," "reality," "the mind," "space," and "time," with no very
definite notion of what they mean.