Early attempts to claim a racial division between "masters" and "slaves", or the belief that a nation's ruling class is biologically superior to its ruled subjects, were made in the 18th century. Henri de Boulainvilliers in his book "History of the Ancient Government of France" (published posthumously in 1727) tried to prove that in France, the nobility represented the descendants of the old Frankish ruling class, whereas the rest of the population was descended from the subject Gauls. Therefore two qualitatively different races were confronting one another, and the only way to abolish the superiority of the Franks was to destroy their civilization. Classical liberal theorists such as Volney and Sieyès discredited this theory by showing that the French nobility consisted mostly of nouveaux riches who came from all parts of the country, and thus the idea of a racially pure Frankish lineage was fraudulent.