Edward Sapir (18841939). Language: An Introduction to the Study of Speech. 1921.
times we may suspect that the resemblance is due to a mere convergence, that a similar morphological feature has grown up independently in unrelated languages. Yet certain morphological distributions are too specific in character to be so lightly dismissed. There must be some historical factor to account for them. Now it should be remembered that the concept of a linguistic stock is never definitive10 in an exclusive sense. We can only say, with reasonable certainty, that such and such languages are descended from a common source, but we cannot say that such and such other languages are not genetically related. All we can do is to say that the evidence for relationship is not cumulative enough to make the inference of common origin absolutely necessary. May it not be, then, that many instances of morphological similarity between divergent languages of a restricted area are merely the last vestiges of a community of type and phonetic substance that the destructive work of diverging drifts has now made unrecognizable? There is probably still enough lexical and morphological resemblance between modern English and Irish to enable us to make out a fairly conclusive case for their genetic relationship on the basis of the present-day descriptive evidence alone. It is true that the case would seem weak in comparison to the case that we can actually make with the help of the historical and the comparative data that we possess. It would not be a bad case nevertheless. In another two or three millennia, however, the points of resemblance are likely to have become so obliterated that English and Irish, in the absence of all but their own descriptive evidence, will have to be set down as unrelated languages. They