earances resulting from
moving x nearer and nearer to the object will approach to a limiting
set, and this limiting set will be that system of appearances which the
object would present if the laws of perspective alone were operative
and the medium exercised no distorting effect. This limiting set of
appearances may be defined, for purposes of physics, as the piece of
matter concerned.

LECTURE VI. INTROSPECTION

One of the main purposes of these lectures is to give grounds for
the belief that the distinction between mind and matter is not so
fundamental as is commonly supposed. In the preceding lecture I dealt in
outline with the physical side of this problem. I attempted to show
that what we call a material object is not itself a substance, but is
a system of particulars analogous in their nature to sensations, and in
fact often including actual sensations among their number. In this
way the stuff of which physical objects are composed is brought into
relation with the stuff of which part, at least, of our mental life is
composed.

There is, however, a converse task which is equally necessary for our
thesis, and that is, to show that the stuff of our mental life is devoid
of many qualities which it is commonly supposed to have, and is not
possessed of any attributes which make it incapable of forming part of
the world of matter. In the present lecture I shall begin the arguments
for this view.

Corresponding to the supposed duality of matter and mind, there are, in
orthodox psychology, two ways of knowing what exists. One of these, the
way of sensation and external perception, is supposed to furnish data
for our knowledge of matter, the other, called "introspection," is
supposed to furnish data for knowledge of our mental processes. To
common sense, this distinction seems clear and easy. When you see a
friend coming along the street, you acquire knowledge of an external,
physical fact; when you realize that you are glad to meet him, you
acquire knowledge of a mental fact. Your dreams and memories and
thoughts, of which you are often conscious, are mental facts, and the
process by which you become aware of them SEEMS to be different from
sensation. Kant calls it the "inner sense"; sometimes it is spoken of
as "consciousness of self"; but its commonest name in modern English
psychology is "introspection." It is this supposed method of acquiring
knowledge of our mental processes that I wish to analyse and exam