Criticism from the left, for example by Sir Ian Kershaw, centered on Nolte's focus on ideas as opposed to social and economic conditions as a motivating force for fascism, and that Nolte depended too much on fascist writings to support his thesis. Kershaw described Nolte's theory of fascism as "resistance to transcendence" as "mystical and mystifying". The American historian Fritz Stern wrote that "The Three Faces of Fascism" was an "uneven book" that was "weak" on "Action Française", "strong" on Fascism and "masterly" on National Socialism.