We have now traced the different stages through which language may pass in attaining to its most perfect form, the inflected stage. There were the two stages in which what we may call the bones of the language were formed, the acquisition of those words which, like _pen_, _ink_ and _paper_, when standing alone bring a definite idea into the mind, and, next, the acquisition of those other words which, like _to_, _for_, _and_, produce no idea in the mind when taken alone. We saw that while the first class of words _may_ have been acquired with any imaginable rapidity, the second class could only have gradually come into use as one by one they fell out of the rank of the ‘significant’ class. Again, after this skeleton of language has been got together, there were, we saw, three other stages which went to make up the grammar of a language: the radical stage, in which all the words of the language can be cut up into _roots_ which are generally monosyllables, each of which has a meaning as a separate word; the agglutinative stage, when the root, _i.e._ the part of the word which expresses the essential idea, remains always distinct from any added portion; and, thirdly, the inflected stage, when in many cases the root and the addition to the root have become so interwoven as to be no longer distinguishable. Of course, really to understand what these three conditions are like, the reader would have to be acquainted with some language in each of the three; but it is sufficient if we get clearly into our heads that there are these stages of language-growth, and that, further, each one of all the languages of the world may be said to be in one of the three. Our opportunities of tracing the history of languages being so limited, we have no recorded instance of a language passing out of one stage into another; but when we examine into these states they so clearly wear the appearance of _stages_ that there seems every reason to believe that a monosyllabic language might in time develop into an agglutinative, and again from that stage into an inflexional, language, _if nothing stopped its growth_. [Sidenote: Arrest in the growth of language.]