The origin of human speech and the mode of its first operation are therefore undiscoverable. We can place no measure to the rapidity with which the first created man may have obtained his stock of words of our first class; as Adam is described naming each one of the animals among whom he lived. All these beginnings lie beyond the ken of linguistic science. But even when he was furnished as fully as we choose to suppose with a class of words which had a meaning of their own, there was still the second class whose invention must have followed upon the invention of the first. The adverbs, prepositions, conjunctions, particles,--the words which meant _to_, _and_, _at_, _but_, _when_,--these we have already seen must as a whole have come into use later than the other class of words. This, then, we may fairly call the second stage in the growth of language, the making of these auxiliary words to enforce the meaning of the first class of words. And at the first moment it might seem impossible to imagine how these words could ever have come into existence. Given a certain word-making faculty, we can understand how mankind got sounds to express such ideas as _man_, _head_, _hard_, _red_. But how he could ever have acquired sounds to express such vague notions as _at_, _by_, _and_, it is much less easy to conceive. A closer observation, however, even of our own language, and a wider knowledge of languages generally, lead to the conclusion that all the words of the second class, the auxiliary words, sprang from words of the first class; that every insignificant word has grown out of a word which had its own significance; that, for instance, _with_, _by_, _and_, have descended from roots (now lost) which, if placed alone, would have conveyed as much idea to the mind as _pen_, _ink_, or _paper_ does to us.