One word more as to the relation between language and thought.  The point of view that we have developed does not by any means preclude the possibility of the growth of speech being in a high degree dependent on the development of thought.  We may assume that language arose pre-rationally—­just how and on what precise level of mental activity we do not know—­but we must not imagine that a highly developed system of speech symbols worked itself out before the genesis of distinct concepts and of thinking, the handling of concepts.  We must rather imagine that thought processes set in, as a kind of psychic overflow, almost at the beginning of linguistic expression; further, that the concept, once defined, necessarily reacted on the life of its linguistic symbol, encouraging further linguistic growth.  We see this complex process of the interaction of language and thought actually taking place under our eyes.  The instrument makes possible the product, the product refines the instrument.  The birth of a new concept is invariably foreshadowed by a more or less strained or extended use of old linguistic material; the concept does not attain to individual and independent life until it has found a distinctive linguistic embodiment.  In most cases the new symbol is but a thing wrought from linguistic material already in existence in ways mapped out by crushingly despotic precedents.  As soon as the word is at hand, we instinctively feel, with something of a sigh of relief, that the concept is ours for the handling.  Not until we own the symbol do we feel that we hold a key to the immediate knowledge or understanding of the concept.  Would we be so ready to die for “liberty,” to struggle for “ideals,” if the words themselves were not ringing within us?  And the word, as we know, is not only a key; it may also be a fetter.

Language is primarily an auditory system of symbols.  In so far as it is articulated it is also a motor system, but the motor aspect of speech is clearly secondary to the auditory.  In normal individuals the impulse to speech first takes effect in the sphere of auditory imagery and is then transmitted to the motor nerves that control the organs of speech.  The motor processes and the accompanying motor feelings are not, however, the end, the final resting point.  They are merely a means and a control leading to auditory perception in both speaker and hearer.  Communication, which is the very object of speech, is successfully effected only when the hearer’s auditory perceptions are translated into the appropriate and intended flow of imagery or thought or both combined.  Hence the cycle of speech, in so far as we may look upon it as a purely external instrument, begins and ends in the realm of sounds.  The concordance between the initial auditory imagery and the final auditory perceptions is the social seal or warrant of the successful issue of the process.  As we have already seen, the typical course of this process may undergo endless modifications or transfers into equivalent systems without thereby losing its essential formal characteristics.