Reiner Schürmann breaks down Heidegger's oeuvre in three periods, each of which corresponds to a transformation of transcendental phenomenology. According to Schürmann's arrangement, the first stage of Heidegger's thought marks the transition from transcendental phenomenology to existential phenomenology. With this transition "the condition of our knowing and experiencing is no longer sought purely in man, but in his relation to the being of entities in their totality."8 The second transformation consists in the passage from the preeminence of Dasein to Menschentum, inaugurated 7 Hans-Georg Gadamer, "Back from Syracuse?" trans. John McCumber, Critical Inquiry, vol. 15, n. 2 (1989), 427-30. 8 Reiner Schürmann, Heidegger on Being and Acting: From Principles to Anarchy (Bloomington: Indiana University Press, 1987), 69. 10 SOFIA PHILOSOPHICAL REVIEW by the "discovery" of destinal history. Suchan existential threat that Western humanity encounters, namely the threat of nihilism.11 Heidegger's first explicit reference to nihilism occurs in his 1935 lecture course published in 1953 under the title Introduction to Metaphysics. There, Heidegger describes nihilism as the cultivation of beings "in the forgetfulness of being."12 Although he will not use the word "nihilism" before 1935, Heidegger had already been developing a diagnosis of imminent nihilism since 1931. This becomes apparent, in the "preliminary considerations" of his 1931-32 lecture course The Essence of Truth. Notwithstanding the fact that the explicit aim of the course is to "consider the essence of truth" by going back to Plato's allegory, Heidegger insists that the return to the originary Greek experience of truth as aletheia is prescribed to us by the