awareness of muscular
contractions as not coming under the head of introspection. I think it
will be found that the essential characteristic of introspective data,
in the sense which now concerns us, has to do with LOCALIZATION: either
they are not localized at all, or they are localized, like visual
images, in a place already physically occupied by something which would
be inconsistent with them if they were regarded as part of the physical
world. If you have a visual image of your friend sitting in a chair
which in fact is empty, you cannot locate the image in your body,
because it is visual, nor (as a physical phenomenon) in the chair,
because the chair, as a physical object, is empty. Thus it seems to
follow that the physical world does not include all that we are aware
of, and that images, which are introspective data, have to be regarded,
for the present, as not obeying the laws of physics; this is, I think,
one of the chief reasons why an attempt is made to reject them. I
shall try to show in Lecture VIII that the purely empirical reasons for
accepting images are overwhelming. But we cannot be nearly so certain
that they will not ultimately be brought under the laws of physics. Even
if this should happen, however, they would still be distinguishable
from sensations by their proximate causal laws, as gases remain
distinguishable from solids.

* "Psychological Review," 1916, "Thought-Content and
Feeling," p. 59. See also ib., 1912, "The Nature of
Perceived Relations," where he says: "'Introspection,'
divested of its mythological suggestion of the observing of
consciousness, is really the observation of bodily
sensations (sensibles) and feelings (feelables)"(p. 427 n.).

(3) CAN WE OBSERVE ANYTHING INTRINSICALLY DIFFERENT FROM SENSATIONS? We
come now to our third question concerning introspection. It is commonly
thought that by looking within we can observe all sorts of things that
are radically different from the constituents of the physical world,
e.g. thoughts, beliefs, desires, pleasures, pains and emotions. The
difference between mind and matter is increased partly by emphasizing
these supposed introspective data, partly by the supposition that matter
is composed of atoms or electrons or whatever units physics may at the
moment prefer. As against this latter supposition, I contend that
the ultimate constituents of matter are not atoms or electrons, but
sensations, and other thing