of words alone.

The more complicated forms of belief tend to consist only of words.
Often images of various kinds accompany them, but they are apt to
be irrelevant, and to form no part of what is actually believed. For
example, in thinking of the Solar System, you are likely to have vague
images of pictures you have seen of the earth surrounded by clouds,
Saturn and his rings, the sun during an eclipse, and so on; but none of
these form part of your belief that the planets revolve round the sun
in elliptical orbits. The only images that form an actual part of such
beliefs are, as a rule, images of words. And images of words, for the
reasons considered in Lecture VIII, cannot be distinguished with any
certainty from sensations, when, as is often, if not usually, the case,
they are kinaesthetic images of pronouncing the words.

It is impossible for a belief to consist of sensations alone, except
when, as in the case of words, the sensations have associations which
make them signs possessed of meaning. The reason is that objective
reference is of the essence of belief, and objective reference is
derived from meaning. When I speak of a belief consisting partly of
sensations and partly of words, I do not mean to deny that the words,
when they are not mere images, are sensational, but that they occur as
signs, not (so to speak) in their own right. To revert to the noise of
the tram, when you hear it and say "tram," the noise and the word are
both sensations (if you actually pronounce the word), but the noise is
part of the fact which makes your belief true, whereas the word is not
part of this fact. It is the MEANING of the word "tram," not the actual
word, that forms part of the fact which is the objective of your
belief. Thus the word occurs in the belief as a symbol, in virtue of
its meaning, whereas the noise enters into both the belief and its
objective. It is this that distinguishes the occurrence of words as
symbols from the occurrence of sensations in their own right: the
objective contains the sensations that occur in their own right, but
contains only the meanings of the words that occur as symbols.

For the sake of simplicity, we may ignore the cases in which sensations
in their own right form part of the content of a belief, and confine
ourselves to images and words. We may also omit the cases in which
both images and words occur in the content of a belief. Thus we become
confined to two cases: (a) when the con