or brandishing its horns, or by uttering fierce sounds.

As the power of intercommunication is certainly of high service to
many animals, there is no _a priori_ improbability in the supposition,
that gestures manifestly of an opposite nature to those by which certain
feelings are already expressed, should at first have been voluntarily
employed under the influence of an opposite state of feeling.
The fact of the gestures being now innate, would be no valid objection
to the belief that they were at first intentional; for if practised
during many generations, they would probably at last be inherited.
Nevertheless it is more than doubtful, as we shall immediately see,
whether any of the cases which come under our present head of antithesis,
have thus originated.

With conventional signs which are not innate, such as those
used by the deaf and dumb and by savages, the principle of
opposition or antithesis has been partially brought into play.
The Cistercian monks thought it sinful to speak, and as they
could not avoid holding some communication, they invented
a gesture language, in which the principle of opposition seems
to have been employed.[2] Dr. Scott, of the Exeter Deaf and
Dumb Institution, writes to me that "opposites are greatly used
in teaching the deaf and dumb, who have a lively sense of them."
Nevertheless I have been surprised how few unequivocal instances
can be adduced. This depends partly on all the signs having
commonly had some natural origin; and partly on the practice
of the deaf and dumb and of savages to contract their signs as much
as possible for the sake of rapidity?[3] Hence their natural
source or origin often becomes doubtful or is completely lost;
as is likewise the case with articulate language.