memory, far better than men of good understandings, well versed in those operations; which is a thing somewhat analogous to the extraordinary sagacity in investigating and concluding, which brutes discover, in respect of some particular things.
Thirdly, The next circumstance which renders brutes far inferior to man in intellectual acquisitions, is their want of symbols, such as words, whereby to denote objects, sensations, ideas, and combinations of ideas. This may appear from several considerations. Those men who happen to be born in a country where the mother tongue is copious and precise, who apply themselves to the study of their mother tongue, who, besides this, learn one or more foreign tongues, &c. get, by these means, a considerable share of the knowledge of things themselves, learn to remark, prove, disprove, and invent, and, cæteris paribus, make a quicker progress in mental accomplishments than others. On the contrary, the mental improvement of persons born deaf is extremely retarded by their incapacity of having things suggested by articulate sounds, or the pictures of these, and also by their not being able to solve the inverse problem, and denote their own trains of thought by adequate symbols. Words are the same kind of helps in the investigation of qualities, as algebraical symbols and methods are in respect of quantity, as has been already remarked. Persons born deaf cannot therefore make any great progress in the knowledge of causes and effects, in abstracted and philosophical matters; but must approach, as it were, to the state of the brute creation. On the contrary, brute creatures, that have much intercourse with mankind, such as dogs and horses, by learning the use of words and symbols of other kinds, become more sagacious than they would otherwise be. And if particular pains be taken with them, their docility and sagacity, by means of symbols, sometimes arise to a very surprising degree.
Parrots might be thought, according to this view of the present subject, to have some particular advantages over quadrupeds, by their being able to pronounce words; since, as has been observed before, the attempts which children make to apply words to things, assist them very much in understanding the applications made by others. But parrots do not seem to speak from any particular acuteness and precision in the auditory nerves, and parts of the brain corresponding thereto, having no cochlea, but from the perfection and pliableness of their vocal organs, in which they exceed other birds; as birds in general do beasts. And it is reasonable to think, that quadrupeds, which resemble man so nearly in the make of the organ of hearing, as well as in other parts, and which also have naturally much more intercourse with man (being fellow-inhabitants of the earth) than birds (which inhabit the air), should likewise have a greater faculty of distinguishing the articulate sounds of man’s voice, retaining their miniatures, and applying them to the things
