While 19th-century racism became closely intertwined with nationalism, leading to the ethnic nationalist discourse that identified the "race" with the "folk", leading to such movements as pan-Germanism, pan-Turkism, pan-Arabism, and pan-Slavism, medieval racism precisely divided the nation into various non-biological "races", which were thought to be the consequence of historical conquests and social conflicts. Michel Foucault traced the genealogy of modern racism to this medieval "historical and political discourse of race struggle". According to him, it divided itself in the 19th century according to two rival lines: on one hand, it was incorporated by racists, biologists and eugenicists, who gave it the modern sense of "race", and they also transformed this popular discourse into a "state racism" (e.g., Nazism). On the other hand, Marxism also seized this discourse founded on the assumption of a political struggle that provided the real engine of history and continued to act underneath the apparent peace. Thus, Marxists transformed the essentialist notion of "race" into the historical notion of "class struggle", defined by socially structured positions: capitalist or proletarian. In "The Will to Knowledge" (1976), Foucault analyzed another opponent of the "race struggle" discourse: Sigmund Freud's psychoanalysis, which opposed the concept of "blood heredity", prevalent in the 19th century racist discourse.