the same time, as it is impossible to treat of the problems of
philosophy except from some point of view, it will be found that, in
Chapters III to XI, a doctrine is presented. It is the same as that
presented much more in detail, and with a greater wealth of reference,
in my "System of Metaphysics," which was published a short time ago.
In the Notes in the back of this volume, the reader will find
references to those parts of the larger work which treat of the
subjects more briefly discussed here. It will be helpful to the
teacher to keep the larger work on hand, and to use more or less of the
material there presented as his undergraduate classes discuss the
chapters of this one. Other references are also given in the Notes,
and it may be profitable to direct the attention of students to them.

The present book has been made as clear and simple as possible, that no
unnecessary difficulties may be placed in the path of those who enter
upon the thorny road of philosophical reflection. The subjects treated
are deep enough to demand the serious attention of any one; and they
are subjects of fascinating interest. That they are treated simply and
clearly does not mean that they are treated superficially. Indeed,
when a doctrine is presented in outline and in a brief and simple
statement, its meaning may be more readily apparent than when it is
treated more exhaustively. For this reason, I especially recommend,
even to those who are well acquainted with philosophy, the account of
the external world contained in Chapter IV.

For the doctrine I advocate I am inclined to ask especial consideration
on the ground that it is, on the whole, a justification of the attitude
taken by the plain man toward the world in which he finds himself. The
experience of the race is not a thing that we may treat lightly.