It is one of the aims of linguistics to define itself, to recognise what belongs within its domain. In those cases where it relies upon psychology, it will do so indirectly, remaining independent.
The first of these phases is that of grammar, invented by the Greeks and carried on unchanged by the French. It never had any philosophical view of a language as such.
Whitney wanted to eradicate the idea that in the case of a language we are dealing with a natural faculty; in fact, social institutions stand opposed to natural institutions.
Linguistics will have to recognise laws operating universally in language, and in a strictly rational manner, separating general phenomena from those restricted to one branch of languages or another.
It is only since linguistics has become more aware of its object of study, i.e. perceives the whole extent of it, that it is evident that this science can make a contribution to a range of studies that will be of interest to almost anyone.
In general, the philological movement opened up countless sources relevant to linguistic issues, treating them in quite a different spirit from traditional grammar; for instance, the study of inscriptions and their language. But not yet in the spirit of linguistics.