To these advantages we may add that words, in being as we have seen less essentially ideographic than gestures, must always have been more available for purposes of abstract expression. We must remember how greatly gesture-language, as it now appears in its most elaborate form, is indebted to the psychologically constructing influence of spoken language; and, thus viewed, it is a significant fact that even now gesture language is not able to convey ideas of any high degree of abstraction. Still, I doubt not it would be possible to construct a wholly conventional system of gestures which should answer to, or correspond with, all the abstract words and inflections of a spoken language; and that then the one sign-system might replace the other—just as the sign-system of writing is able similarly to replace that of speech. This, however, is a widely different thing from supposing that such a perfect system of gesture-signs could have grown by a process of natural development; and, looking to the essentially ideographic character of such signs, I greatly question whether, even under circumstances of the strongest necessity (such as would have arisen if man, or his progenitors, had been unable to articulate), the language of gesture could have been developed into anything approaching a substitute for the language of words. It may tend to throw some light on this hypothetical question—which is of some importance for us—if we consider briefly the psychological _status_ of wholly uneducated deaf-mutes; for although it is true that their case is not fairly parallel to that of a human race destitute of the faculty of speech (seeing that the individual deaf-mute does not find any elaborate system of signs prepared for him by the exertions of dumb ancestors, as would doubtless have been the case under the circumstances supposed), still, on the other hand, and as a compensating consideration, we must remember that the individual deaf-mute not only inherits a human brain, the structure of which has been elaborated by the speech of his ancestors, but is also surrounded by a society the whole structure of whose ideation is dependent upon speech. So far, therefore, as the complex conditions of the question admit of being disentangled, the case of uneducated deaf-mutes living in a society of speaking persons affords the best criterion we can obtain of the prospect which gesture-language would have had as a means of thought-formation in the human race, supposing this race to have been destitute of the faculty of speech. To show, therefore, the psychological condition of an individual thus circumstanced, I will quote a brief passage from a lecture of my own, which was given before the British Association in 1878.