Or, to take an example from a modern inflected language, if the _-es_ of _Mannes_, expresses a certain idea relative to _Mann_, so does the same inflexion (_-es_ or _-s_) in _Hauses_, _Baums_, etc., relative to _Haus_ and _Baum_.
Now, how are we to explain this fact? Our grammars, it is true, take it for granted, and give it us as a thing which requires no explanation--the genitive inflexion is _-nis_ or _-es_, or whatever it may be. That is all they tell us. But we cannot be content to take anything of course. An explanation, however, is not difficult, and follows, _almost_ of course, on the exercise of a little common sense. If the _-es_ of Mannes, Hauses, Baumes (Baums) expresses the idea ‘of,’ then, at one time or another, _es_, or some root from which it is derived, must have _meant_ ‘of.’ This explains easily and naturally enough the inflexions in any inflected language. They have no meaning now, but at one time they (or their original forms--their ancestors, so to speak) had no doubt just as much meaning by themselves as our ‘of.’ And therefore the only difference between our use in England to-day, and the ancestral use in a primitive language, was that we say ‘of [the] man,’ and the ancestral language would have said ‘man-of,’ ‘house-of,’ etc. This accounts for the same genitive forms being used for so many different words.
And that the same genitive forms are not used _throughout_ any language is no real objection to this theory. If we say _dictionis_, _lectionis_, but _musæ_, _rosæ_; if we say _Mannes_, _Hauses_, but _Blume_, _Rose_, the only reason of these varieties is that the languages from which these inflexions are derived possessed more than one word meaning ‘of,’ and that one of these words was attached to a certain series of nouns, another word to another series.
This is the explanation which mere common sense would give of the origin of inflexions in language, and further research, had we time to examine the history of language more elaborately, would show that it was _fundamentally_ the right explanation. The only correction which we should have to make on this first and crude theory is explained a little further on. Thus we see in this third stage of language a process very closely analogous to the second. The second stage gave us the auxiliary words, which have decayed so to say, out of the class of significant words. The third stage gives us the auxiliary words joined on to the significant ones, and in their turn decaying to become mere inflexions.