The sense (not a properly generic one) in which the witnesses of the Holocaust created a new literature of testimony, is much the same sense as that in which the witnesses of the history of Jesus created the Gospels. Those witnesses understood the imperative to witness to a command of the risen Christ, but the parallel is sufficient to be suggestive. In both cases, the uniqueness required precisely witness as the only means by which the events could be adequately known. In both cases, the exceptionality of the event means that only the testimony of participant witnesses can give us anything approaching access to the truth of the event. In the case of the holocaust, again Wiesel puts it famously: “the truth of Auschwitz is hidden in its ashes. Only those who lived it in their flesh and in their minds can possibly transform it into knowledge.”
Richard Bauckham, Jesus and the Eyewitnesses: The Gospels as Eyewitness Testimony (Grand Rapids, MI: 2006), 499-502.