The Cambridge History of English and American Literature in 18 Volumes (1907–21).
VOLUME XVIII. Later National Literature, Part III.

XXXI. Non-English Writings I

§ 36. Judæo-German

It is very difficult to set geographical limits to Yiddish literature. American Yiddish authors were all born in Europe, and it is quite natural for them to revert to themes of the old home. The constant intercourse among Jewish authors in both hemispheres and the mutual influence exerted render geographical divisions still more artificial. Yet it’s necessary, in the interests of orientation, to omit authors only indirectly related to American Yiddish literature and to dwell only on those who have settled permanently in the United States and whose works reflect the life of the Jewish immigrants.

Judæo-German, now known as Yiddish, branched out from the German during the latter half of the sixteenth century when German Jews settled in compact masses in the Slavic countries. The vernacular developed by the Jews there gradually departed from the original dialect and became distinct from it, and today idiomatic Yiddish bears only a remote resemblance to the German. Many Hebrew words ingrained in the body of Yiddish, together with numerous words and expressions borrowed from contiguous Slavic vernaculars and thoroughly assimilated, make Yiddish a distinct linguistic unit.