That thought cannot exist without speech, is a truth generally admitted.
The negations of this thesis are all founded on equivoques and errors.

The first of the equivoques is implied by those who observe that one can
likewise think with geometrical figures, algebraical numbers,
ideographic signs, without a single word, even pronounced silently and
almost insensibly within one. They also affirm that there are languages
in which the word, the phonetic sign, expresses nothing, unless the
written sign also be looked at. But when we said "speech," we intended
to employ a synecdoche, and that "expression" generically, should be
understood, for expression is not only so-called verbal expression, as
we have already noted. It may be admitted that certain concepts may be
thought without phonetic manifestations. But the very examples adduced
to show this also prove that those concepts never exist without
expressions.

Others maintain that animals, or certain animals, think or reason
without speaking. Now as to how, whether, and what animals think,
whether they be rudimentary, half-savage men resisting civilization,
rather than physiological machines, as the old spiritualists would have
it, are questions that do not concern us here. When the philosopher
talks of animal, brutal, impulsive, instinctive nature and the like, he
does not base himself on conjectures as to these facts concerning dogs
or cats, lions or ants; but upon observations of what is called animal
and brutal in man: of the boundary or animal basis of what we feel in
ourselves. If individual animals, dogs or cats, lions or ants, possess
something of the activity of man, so much the better, or so much the
worse for them. This means that as regards them also we must talk, not
of their nature as a whole, but of its animal basis, as being perhaps