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 practiced 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. 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. Hence their natural source or origin often becomes doubtful, or is completely lost; as is likewise the case with articulate language. * * * * * [Page 64.] When a cat, or rather when some early progenitor of the species, from feeling affectionate, first slightly arched its back, held its tail perpendicularly upward and pricked its ears, can it be believed that the animal consciously wished thus to show that its frame of mind was directly the reverse of that when, from being ready to fight or to spring on its prey, it assumed a crouching attitude, curled its tail from side to side, and depressed its ears? Even still less can I believe that my dog voluntarily put on his dejected attitude and “_hot-house face_,” which formed so complete a contrast to his previous cheerful attitude and whole bearing. It can not be supposed that he knew that I should understand his expression, and that he could thus soften my heart and make me give up visiting the hot-house.