The theory alluded to is that climate, and the environment it controls, determine the character of peoples - or, in the language of the centuries mentioned, that it determines the prevailing 'humours', the nature and character tendencies of nations. This idea goes back at least to Hippocrates and other medical men of ancient Greece around 400 BC. Aristotle (384-322 BC) already used the notion of prevailing characteristics of people in the cold, warm and middle zones of the Earth to expound the superior qualities ofthe Hellenes as a master race which, if only they could be united, should be able to rule the world. We should, perhaps, see this theory as having been a proposition by which to learn about the world and human nature; but we must note the dangers to which too popular, glib applications of the theory directly led. Of such applications there have been many.