ed to refute a theory which is widely held,
and which I formerly held myself: the theory that the essence of
everything mental is a certain quite peculiar something called
"consciousness," conceived either as a relation to objects, or as a
pervading quality of psychical phenomena.

The reasons which I shall give against this theory will be mainly
derived from previous authors. There are two sorts of reasons, which
will divide my lecture into two parts:

(1) Direct reasons, derived from analysis and its difficulties;

(2) Indirect reasons, derived from observation of animals (comparative
psychology) and of the insane and hysterical (psycho-analysis).

Few things are more firmly established in popular philosophy than the
distinction between mind and matter. Those who are not professional
metaphysicians are willing to confess that they do not know what mind
actually is, or how matter is constituted; but they remain convinced
that there is an impassable gulf between the two, and that both belong
to what actually exists in the world. Philosophers, on the other hand,
have maintained often that matter is a mere fiction imagined by mind,
and sometimes that mind is a mere property of a certain kind of matter.
Those who maintain that mind is the reality and matter an evil dream are
called "idealists"--a word which has a different meaning in philosophy
from that which it bears in ordinary life. Those who argue that matter
is the reality and mind a mere property of protoplasm are called
"materialists." They have been rare among philosophers, but common,
at certain periods, among men of science. Idealists, materialists, and
ordinary mortals have been in agreement on one point: that they knew
sufficiently what they meant by the words "mind" and "matter" to be able
to conduct their debate intelligently. Yet it was just in this point, as
to which they were at one, that they seem to me to have been all alike
in error.

The stuff of which the world of our experience is composed is, in my
belief, neither mind nor matter, but something more primitive than
either. Both mind and matter seem to be composite, and the stuff of
which they are compounded lies in a sense between the two, in a sense
above them both, like a common ancestor. As regards matter, I have set
forth my reasons for this view on former occasions,* and I shall not now
repeat them. But the question of mind is more difficult, and it is this
question that I propose to discu