[…] when the ethnological relations of a community or of a group of communities are to be settled, the first question is as to the affinities of its speech. This does not necessarily decide the case; the linguistic evidence may be overborne by some other; but nothing can be determined without it; it lays the basis for further discussion.
- Whitney (1875), Pag. 275

The linguistic evidence has over […] the physical the advantage that it is far more abundant and varied, and therefore manageable.
- Whitney (1875), Pag. 273