This chapter reviews how Martin Heidegger's interpretation of being-true is grounded in the soul's manner of being-disposed. It addresses Heidegger's appropriation of Aristotle's account of the two basic forms of pathos, namely, the tranquil mood of being-composed and the fearful mood of being-decomposed. The chapter shows how this pathology of truth de-poses one. This pathology of truth reflects how Dasein finds itself oriented toward its ownmost possibility, its possibility-to-be. It is nothing other than openness to this possibility. Dasein preserves its possibility-to-be as a possibility of being-composed by hedone and the mood of tranquility. Yet this possibility of becoming composed is always openness to becoming de-composed. Pathos embodies this movement so that Dasein in becoming-what-it-is finds itself posed with the possibility of becoming-what-it-is not. Dasein only encounters beings by first being-out-towards its nullity or absence as the most distinctive possibility of its finite existence.