In 1909, Péguy spoke out against a collective withdrawal at a time when he personally started to embrace his vocation as a writer. But he was also writing on the threshold of a new era that will be marked by historical catastrophes. Péguy hardly ever wrote testimonies in the strict sense of the term, but his Cahiers and his work itself embrace all the issues (religious, legal, epistemic) at stake in this genre’s relationship to the issue of historicity. This is why he stands at the crystallization point of testimony as a genre, participating in the reflection on the restitution of a lived truth that a subject guarantees through his speech and writing.