 Deleuze’s historically oriented study at the Sorbonne led him to devote his first book, Empiricism and Subjectivity (1953), to Hume. In an era in which peers like Foucault and Derrida, students at the École Normale Supérieure, concentrated on “the three ‘H’s” (Hegel, Husserl, Heidegger), Deleuze’s decision to write on empiricism and Hume was already a provocation, early evidence of the heterodox tendencies of his thought. From 1953 to 1962—which he later referred to as “a hole in my life”—Deleuze published little, moving among various teaching positions in Paris and the provinces. It was also during this time that he contracted the recurring respiratory ailment that would plague him for the rest of his life. In 1962, Nietzsche and Philosophy was published to considerable acclaim, cementing Deleuze’s reputation in academic circles. He followed this initial success with Kant’s Critical Philosophy (1963); Proust and Signs (1964); and Bergsonism (1966). In 1968 he published Difference and Repetition as his primary thesis for the doctorat d’État, with Spinoza and the Problem of Expression as the secondary thesis.