"[l]anguage, albeit an abstraction, is yet a more subtle and pervasive criterion of individuality than the culture-group formed by comparing flints and potsherds or the “races” of the skull-measurer. . . . they [the Aryans] must have possessed a certain spiritual unity reflected in and conditioned by their community of speech. To their linguistic heirs they bequeathed, if not skull types and bodily characteristics, at least something of this more subtle and precious, spiritual identity. . . . The Indo-European languages and their presumed parent-speech have been throughout exceptionally delicate and flexible instruments of thought. They were almost unique, for instance, in possessing a substantive verb and at least a rudimentary machinery for building subordinate clauses that might express conceptual relations in a chain of ratiocination. It follows then that the Aryans must have been gifted with exceptional mental endowments, if not in enjoyment of a high material culture. (p. 4)"