The next point which I desire to consider is that, although gesture language is not in my opinion so efficient a means of developing abstract ideation as is spoken language, it must nevertheless have been of much service in assisting the growth of the latter, and so must have been of much service in laying the foundation of the whole mental fabric which has been constructed by the faculty of speech. Whether we look to young children, to savages, or in a lesser degree to idiots, we find that gesture plays an important part in assisting speech; and in all cases where a vocabulary is scanty or imperfect, gesture is sure to be employed as the natural means of supplementing speech. Therefore, supposing speech to have had a natural mode of genesis, it is, in my opinion, perfectly certain that its origin and development must have been greatly assisted by gesture. In subsequent chapters I will adduce direct evidence upon this head. At present I wish to draw attention to another point. This is, that although gesture psychologically precedes speech, when once articulate sounds have been devised for the expression of ideas, the faculty of using these articulate sounds as signs of their corresponding ideas does not involve the presence of a higher psychological development than does the faculty of using tones and gestures for the conveyance of similar ideas. As already shown, it is a matter of observable fact that the only animals which are able to articulate are able to employ nouns, adjectives, and verbs, as expressive of concrete ideas; while animals which are not able to articulate similarly employ tones, and in many cases are able to understand words. Therefore, it is a matter of observable fact that the psychological level required for using tones as vocal gestures, understanding words as expressive of simple ideas, and even uttering words with a correct appreciation of their meaning, is a level not higher than that which obtains in some existing animals. If we turn from animals to man, we find the same truth exemplified. For in the descending grade of human intelligence as exhibited by idiots, we see that while the use of simple gestures as signs occurs in idiots somewhat too low in the scale to utter any articulate words, nevertheless the interval between such an idiot and one capable of uttering the simplest words is a short interval. Again, in the ascending grade of human intelligence, as exhibited by the growing child, we find the same observation to apply; although, on account of some children requiring a longer time than others to develop the _mechanique_ of articulation, we might by considering their cases alone over-estimate the psychological interval which separates gesticulation from speech.[91]