 Arendt's first major book, "The Origins of Totalitarianism" (1951), examined the roots of Communism and Nazism, structured as three essays, "Antisemitism", "Imperialism" and "Totalitarianism".Arendt argues that totalitarianism was a "novel form of government," that "differs essentially from other forms of political oppression known to us such as despotism, tyranny and dictatorship" in that it applied terror to subjugate mass populations rather than just political adversaries.Criticism included the interpretation that the two movements were portrayed as equally tyrannical.