The French philosopher Charles Péguy (1873-1914) addressed a problem of fundamental importance in modern and contemporary philosophy: the relation between time and ethics. This PhD proposes an analysis of this relation as its finds its philosophical expression in Péguy's later works dealing with the Christian doctrine of Incarnation. This problem will be carefully situated within its politico-ethical condition of appearance, forestalling any interpretation which would unduly separate Péguy's early, more political writings from his posthumous philosophical publications. It will be argued that the relation between time and ethics first appeared as a concern, when the Dreyfus Affaire disclosed the incompatibility of his reformist socialist ethics with a socialdemocratic, modern consciousness of time. Moderns transform time into a space by which to measure succession. In so doing, they undercut the very conditions of possibility of cultivating an ethical relation to oneself. The Christian doctrine of Incarnation, to the contrary, transforms the present from an instrument of measurement into the point of passage for being, inventing the formal condition of possibility for all internal life. This study hopes to contribute to contemporary discussions on presentist ethics.