physics does not assume the existence of matter.

The view that seems to me to reconcile the materialistic tendency
of psychology with the anti-materialistic tendency of physics is
the view of William James and the American new realists,
according to which the "stuff" of the world is neither mental nor
material, but a "neutral stuff," out of which both are
constructed. I have endeavoured in this work to develop this view
in some detail as regards the phenomena with which psychology is
concerned.

My thanks are due to Professor John B. Watson and to Dr. T. P.
Nunn for reading my MSS. at an early stage and helping me with
many valuable suggestions; also to Mr. A. Wohlgemuth for much
very useful information as regards important literature. I have
also to acknowledge the help of the editor of this Library of
Philosophy, Professor Muirhead, for several suggestions by which
I have profited.

The work has been given in the form of lectures both in London
and Peking, and one lecture, that on Desire, has been published
in the Athenaeum.

There are a few allusions to China in this book, all of which
were written before I had been in China, and are not intended to
be taken by the reader as geographically accurate. I have used
"China" merely as a synonym for "a distant country," when I
wanted illustrations of unfamiliar things.

Peking, January 1921.