All historically great races and nations have been produced by mixing; but wherever the difference of type is too great to be bridged over, then we have mongrels. That is the case here. The crossing between Bedouin and Syrian was — from an anatomical point of view — probably worse than that between Spaniard and South American Indian.

The Foundations of the Nineteenth Century (Die Grundlagen des neunzehnten Jahrhunderts) (1899)