Because, in the states which we know to have been peopled by the Pelasgi (as Arcadia and Attica), and whence the population were not expelled by new tribes, the language appears no less Greek than that of those states from which the Pelasgi were the earliest driven.

Had they spoken a totally different tongue from later settlers, I conceive that some unequivocal vestiges of the difference would have been visible even to the historical times.
2dly.

Because the Hellenes are described as few at first--their progress is slow--they subdue, but they do not extirpate; in such conquests--the conquests of the few settled among the many--the language of the many continues to the last; that of the few would influence, enrich, or corrupt, but never destroy it.
3dly.

Because, whatever of the Grecian language pervades the Latin [7], we can only ascribe to the Pelasgic colonizers of Italy.

In this, all ancient writers, Greek and Latin, are agreed.