Our lecture will engage firstly in deploying a phenomenological investigation of the idea of singularity and, from this study, reveal at once the concealed modalities and the novel possibilities reserved in this idea from which we shall develop the lineaments of a phenomenology of history oriented towards deploying an approach of the unthinkable in historical events. Retrieving the Husserlian and Heideggerian interpretations of “history” as well as the pointed analyses developed in Ricoeur, Derrida, Levinas and Patocka, we will develop a philosophical problematization of “truth” and “reason”, “testimony” and “memory” in history by putting forth a suspension of these conceptual figures and where we will see emerge the significance of an economy of sacrifice as the essential element in which the incessant play between “polis” and “polemos” shows itself as History. Through this extensive analysis, we shall propose the possibility of shifting our thinking of past historical events as always futural and to come in our lived-present and where aporetically occurs the persistent call for an idea of justice in the name of the irreducible singularity in historical events. What occurs to our lived-present in the face of the singularity of unthinkable futures arising out of each past historical event? What regime of signification can be constituted and instituted for the singularity of past historical events occurring in our lived-present as exceptionally futural? Our lecture will hence put forth a certain idea of justice for each singular historical event which resists the sacrificial economies of historical consciousness and which will be seen to open towards a novel concept of “historical mindfulness”, one calling onto an unconditional and unconditioned responsibility for the singular.