This highly general and most important fact is usually stated as it was, I believe, first stated by the anthropologist Waitz, namely, that “the unit of language is not the word, but the sentence;”[219] and, therefore, that historically the sentence preceded the word. Or, otherwise and less ambiguously expressed, every word was originally itself a proposition, in the sense that of and by itself it conveyed a statement. Of course the more that a single word thus assumed the functions now discharged by several words when built into a proposition, the more generalized—that is to say, the less defined—must have been its meaning. The sentence or proposition as we now have it represents what may be termed a psychological division of labour as devolving upon its component parts: subject-words, attributive-words, qualifying-words indicative of time, place, agent, instrument, and so forth, are now all so many different organs of language, which are set apart for the performance of as many different functions of language. The life of language under this its fully evolved form is, therefore, much more complex, and capable of much more refined operations, than it was while still in the wholly undifferentiated condition which we have now to contemplate. In order to gain a clear conception of this protoplasmic condition of language, we had better first take an example of it as it is presented to our actual observation in the child which is just beginning to speak. For instance, as Professor Max Müller points out, “if a child says ‘Up,’ that _up_ is, to his mind, noun, verb, adjective, all in one. If an English child says ‘Ta,’ that _ta_ is both noun (thanks), and a verb (I thank you). Nay, even if a child learns to speak grammatically, it does not yet think grammatically; it seems, in speaking, to wear the garments of its parents, though it has not yet grown into them.”[220] Again, as Professor Friedrich Müller says, “the child’s word _Ba-ba_, sleep, does not mean sleep only, as a particular kind of repose, but rather also all the circumstances which appertain to sleep, such as cot, bed, bolster, bed-clothes, &c.[221] It likewise and indifferently means, sleeping, sleepy, sleeper, &c., and may stand for any variety of propositions, such as “I am sleepy,” “I want to go to sleep,” “He is asleep,” &c.