Adolf Hitler: Mein Kampf(1926)
Chapter XI: Nation and Race
There are some truths which are so obvious that for this very reason they are not seen or at least not recognized by ordinary people. They sometimes pass by such truisms as though blind and are most astonished when someone suddenly discovers what everyone really ought to know. Columbus's eggs lie around by the hundreds of thousands, but Columbuses are met with less frequently.
Thus men without exception wander about in the garden of Nature; they imagine that they know practically everything and yet with few exceptions pass blindly by one of the most patent principles of Nature's rule: the inner segregation of the species of all living beings on this earth.
Even the most superficial observation shows that Nature's restricted form of propagation and increase is an almost rigid basic law of all the innumerable forms of expression of her vital urge. Every animal mates only with a member of the same species. The titmouse seeks the titmouse,...
Source: Adolf Hitler. Mein Kampf. Translated by Ralph Manheim. Boston, MA: Houghton Mifflin, 1971.
Adolf Hitler (center) in a Munich garden café (Yale University Art Gallery)View Full Size