Aristotle found support for his thesis in facts drawn from geopolitics or 'natural law'. Greek superiority had to be proved demonstrably innate, a gift of nature. In one celebrated fragment he counsels Alexander to be 'a hegemon [leader] of Greeks and a despot to the barbarians, to look after the former as after friends and relatives, and to deal with the latter as with beasts or plants'.

Alexander of Macedon, 356-323 B.C.: A Historical Biography, page 58.