Gobineau's influence was slight at first. In his letters to Alexis de Tocqueville, he complained that his book was being hushed up in France and was having a real effect only in the United States. Tocqueville, who rejected the book in spite of his friendship with Gobineau, pointed out to him that this was because the book chimed with the slave-owners' interests in the Southern states. However, in the 1880s the book gained popularity in Germany thanks to the efforts of Cosima Wagner. In 1899, Houston Stewart Chamberlain, a Germanophile Englishman and Cosima Wagner's son-in-law, published "The Foundations of the Nineteenth Century". Expanding upon Gobineau's earlier theories, he argued that Western civilization is deeply marked by the influence of the Teutonic peoples. Chamberlain grouped all European peoples—not just Germans, but Celts, Slavs, Greeks, and Latins—into the "Aryan race", a race built on the ancient Proto-Indo-European culture. At the helm of the Aryan race, and, indeed, all races, he saw the Nordic or Teutonic peoples.