The fact that the languages commonly learnt by Europeans belong mostly to the same Aryan stock, and have besides a large vocabulary in common of borrowed Latin, French, and greek words, is apt to blind them to a recognition of the fact that the real intrinsic difficulty of learning a foreign language lies in that of having to master its vocabulary. (…)
We can master enough of the grammar of any language for reading purposes within a definite period – generally less than six months – but we cannot do the same with the vocabulary unless it is already partially familiar to us in the way that the vocabulary of Italian is to all English speakers. (…)
It is evident that every language in its colloquial form must be adapted to the average capacity of its speakers. Although each language is constructed to a great extent by the philosophers and poets of the race, it cannot in the form of it which serves for ordinary intercourse go beyond the capacity of the average mind. Learning a language, therefore, is not in any way analogous to learning mathematics or metaphysics: it does not imply any attempt to enter into higher regions of thought – to commune with a higher mind. On the contrary, as the greater part of all existing languages was evolved by people in a rudimentary state of civilization, it implies the very reverse. Hence, it is often a positive obstacle to learning a language to be rigorously logical and minutely analytical. (…)
(pp. 64-68)