262 An Essay on the Signs of Ideas. 
Locke, that we frequently think by words, 
and not by ideas. Yet even in the cases 
where we say that we think by. words, we 
must recollect, that it is only by the ideas of 
words ;—that is, either of written words, as 
received by the sense of vision, or of spoken 
words, as received by the sense of hearing. 
So that, in every case, thought consists in the 
consciousness of ideas. 
Of the third kind of words, not represent- 
ing ideas, are such as are the names of things 
having, as we suppose, (and, no doubt in many 
cases, correctly suppose,) a real existence, 
though we certainly can form no conception 
of them. Of this kind are the term cold, 
when used for a real material agent, and not 
for the name of a sensation, the word heat, 
used in the same manner, the electric fluid, 
the galvanic fluid, the principium vite or 
principle of life, of some medical philoso- 
phers, and the nervous fluid, of others. With 
respect to the sacred name of the Supreme 
Being, much might be said, were it not a 
subject toosolemn for us lightly to dwell upon 
it in the illustrating of our comparatively 
trifling speculations. It may be remarked, 
however, that though all mankind, probably 
without exception, are convinced of the ex- 
istence of such a Being, no one, we may 
