The Foundations of the Nineteenth Century (Die Grundlagen des neunzehnten Jahrhunderts, 1899) is a racialist book by the British-German-French philosopher Houston Stewart Chamberlain.

In the book, Chamberlain advances various racialist and especially völkisch antisemitic theories on how he saw the Aryan race as superior to others, and the Teutonic peoples as a positive force in European civilization and the Jews as a negative one.

Published in German, the book advocates a form of Nordicism and focuses on the controversial pseudoscientific notion that Western civilization is deeply marked by the influence of the Teutonic peoples.

[2] Chamberlain's book focused on the claim that the Teutonic peoples were the heirs to the empires of Greece and Rome, something which Charlemagne and some of his successors also believed.

Chamberlain's thoughts were influenced by the writings of Arthur de Gobineau (1816–1882), who had argued the superiority of the "Aryan race".

According to Chamberlain, the modern Jew (Homo judaeica) mixes some of the features of the Hittite (H. syriaca) – notably the "Jewish nose", retreating chin, great cunning and fondness for usury[3] – and of the true Semite, the Bedouin Arab (H. arabicus), in particular the dolichocephalic (long and narrow) skull, the thick-set body, and a tendency to be anti-intellectual and destructive.

Chamberlain's admirer Adolf Hitler held a similar view, as evidenced in his table talk, where he canvassed the idea of Jesus as the illegitimate son of a Roman soldier stationed in Galilee.

"[12] The book was important to Wilhelm II, who became Chamberlain's friend (the two held a correspondence), and as a "spiritual" foundation of the Third Reich.