There are certain truths which stand out so openly on the roadsides of life that every passer-by may see them.
Yet, because of their very obviousness, the general run of people disregard such truths or at least they do not make them the object of any conscious knowledge. People are so blind to some of the simplest facts in everyday life that they are highly surprised when somebody calls attention to what everybody ought to know all the innumerable forms in which the life-urge of Nature manifests itself are subject to a fundamental law–one may call it an iron law of Nature–which compels the various species to keep within the definite limits of their own life-forms when propagating and multiplying their kind.
Each animal mates only with one of its own species. The titmouse cohabits only with the titmouse, the finch with the finch, the stork with the stork, the field-mouse with the field-mouse, the house-mouse with the house-mouse, the wolf with the she-wolf, etc.
Every crossing between two breeds which are not quite equal results in a product which holds an intermediate place between the levels of the two parents. This means that the offspring will indeed be superior to the parent which stands in the biologically lower order of being, but not so high as the higher parent. For this reason it must eventually succumb in any struggle against the higher species. The stronger must dominate and not mate with the weaker. This urge for the maintenance of the unmixed breed, which is a phenomenon that prevails throughout the whole of the natural world, results not only in the sharply defined outward distinction between one species and another but also in the internal similarity of characteristic qualities which are peculiar to each breed or species.
If Nature does not wish that weaker individuals should mate with the stronger, she wishes even less that a superior race should intermingle with an inferior one; because in such a case all her efforts, throughout hundreds of thousands of years, to establish an evolutionary higher stage of being, may thus be rendered futile. If we review all the causes which contributed to bring about the downfall of the German people we shall find that the most profound and decisive cause must be attributed to the lack of insight into the racial problem and especially in the failure to recognize the Jewish danger.
By neglecting the problem of preserving the racial foundations of our national life, the old Empire abrogated the sole right which entitles a people to live on this planet. Nations that make mongrels of their people, or allow their people to be turned into mongrels, sin against the Will of Eternal Providence. And thus their overthrow at the hands of a stronger opponent cannot be looked upon as a wrong but, on the contrary, as a restoration of justice.
If a people refuses to guard and uphold the qualities with which it has been endowed by Nature and which have their roots in the racial blood, then such a people has no right to complain over the loss of its earthly existence. Everything on this earth can be made into something better, provided always that the racial blood is kept pure. But the loss of racial purity will wreck inner happiness forever. It degrades men for all time to come. And the physical and moral consequences can never be wiped out.
If this unique problem be studied and compared with the other problems of life we shall easily recognize how small is their importance in comparison with this. They are all limited to time; but the problem of the maintenance or loss of the purity of the racial blood will last as long as man himself lasts. The black-haired Jewish youth lies in wait for hours on end, satanically glaring at and spying on the unsuspicious girl whom he plans to seduce, adulterating her blood and removing her from the bosom of her own people.
The Jew uses every possible means to undermine the racial foundations of a subjugated people. In his systematic efforts to ruin girls and women he strives to break down the last barriers of discrimination between him and other peoples. The Jews were responsible for bringing negroes into the Rhineland, with the ultimate idea of bastardizing the white race which they hate and thus lowering its cultural and political level so that the Jew might dominate. For as long as a people remain racially pure and are conscious of the treasure of their blood, they can never be overcome by the Jew. Never in this world can the Jew become master of any people except a bastardized people. That is why the Jew systematically endeavours to lower the racial quality of a people by permanently adulterating the blood of the individuals who make up that people. The Star of David steadily ascended as the will to National Self-Preservation declined.
(Excerpts from Mein Kampf, Chapter XI: Nation and Race)