The intellectual level of such persons is very low (we shall return to this): still their inferiority has been exaggerated, especially in the last century, by virtue of the axiom, it is impossible to think without words. Discussion of this antique aphorism is unnecessary; in its rigorous form it finds hardly any advocates of note.[29] Since thought is synonymous with comparing, abstracting, generalising, judging, reasoning, i. e., with transcending in any way the purely sensorial and affective life, the true question is not, Do we think without words? but, To what extent can we think without words? Otherwise expressed, we have to fix the upper limit of the logic of images, which evidently reaches its apogee in adult deaf-mutes. Further, even in this last case, thought without language does not attain its full development. The deaf-mute who is left without special education, and who lives with men who have the use of speech, is in a less favorable situation than if he forms a society with his equals. Gérando, and others after him, remarked that deaf-mutes in their native state communicate easily with one another. He enumerates a long series of ideas, which they express in their mimicry, and gestures, and many of these expressions are identical in all countries. “Children of about seven years old who have not yet been educated, make use of an astonishing number of gestures and very rapid signs in communicating with each other. _They understand each other naturally with great facility_.... No one teaches them the initial signs, which are, in great part, unaltered imitative movements.” The study of this spontaneous, natural language is the sole process by which we can penetrate to their psychology, and determine their mode of thought. Like all other languages, it comprises a vocabulary and a syntax. The vocabulary consists in gestures which designate objects, qualities, acts; these correspond to our substantives and verbs. The syntax consists in the successive order of these gestures and their regular arrangement; it translates the movement of thought and the effort towards analysis. I. VOCABULARY—Gérando collected about a hundred and fifty signs, created by deaf-mutes living in isolation or with their fellows.[30] A few of these may be cited as examples: _Child_—Infantile gesture, of taking the breast, or being carried, or rocking in the cradle. _Ox_—Imitation of the horns, or the heavy tread, or the jaws chewing the cud. _Dog_—Movement of the head in barking. _Horse_—Movements of the ears, or two figures riding horseback on another, etc. _Bird_—Imitation of the beak with two fingers of the left hand, while the other feeds it; or simulation of flight. _Bread_—Signs of being hungry, of cutting, and of carrying to the mouth. _Water_—Exhibition of saliva, imitation of a rower, or of a man pumping; accompanied always by the sign of drinking. _Letter_ (missive)—Gestures of writing and of sealing, or of unsealing and reading.