s. It will also add to the facility of the experiment, that
he select a subject with which he is but little acquainted, as the
process will be more deliberate. On topics with which we are familiar,
we have acquired a rapidity of exercise which renders the detection of
the process more difficult and perplexing. In this trial, he will be
aware that he is repeating words as the materials of his thoughts. If
the subject on which he should think involves persons with whom he is
acquainted, or scenes he has viewed, he will, in addition to the terms
he employs, have the pictures, or visible phantasmata, of these
presented to his mind, conjunctively with such words. That we actually
employ terms in this process is evident in many, who, when exercising
their thoughts on any subject, are found, as we term it, talking to
themselves; so that we are enabled to observe the motion of their lips:
and this circumstance is to be noticed in most persons when they are
counting.

The contrivances of language enable us to connect our thoughts; for our
perceptions are distinct and individual, and of themselves can possess
no elective attraction to _associate_ and combine: they may however, by
repetition or habit, become so allied, that the occurrence of one will
excite the sequence of the other. We ordinarily recollect them very much
in the order and succession of their occurrence; but we are also able
to arrange and class them, and by such means, of recollecting them
according to the artificial order of their distribution. This may be
exemplified in the various expedients that have been devised for the
acquirement and retention of knowledge: thus, chronology records events
according to the order of their occurrence; an encyclopaedia arranges
according to alphabet or subject; and the most perfect of this kind,
like the index to a book, consists in their mutual reference.

This wonderful faculty of thought or reflection, so far as we possess
the means of detecting, appears to be peculiar to man; and if it be
admitted to consist of our recollected perceptions, by the contrivances
of language, we shall find that animals are not in possession of the
necessary materials.

The ear transmits sounds to animals possessing this sense; and in some
species it is so exquisitely susceptible, as to surpass, by many
degrees, the acuteness of the same organ in the human subject. It is
also recorded, that in some of the wilder tribes of man, the hearing
pos