In the 13th and 14th centuries, the very notion of proof took root in the tension between the necessary reconstruction of absent facts in order to render them knowable, and the consciousness of the impossibility of such a recreation. As with common law, the whole logic of proof in the Alphonsian texts is that of belief, of which there can be three modes: the first concerns the witnesses as well as the judge and is determined by means of sensorial perception: one says that one believes that which one has heard, whereas knowledge comes from seeing. The second type of belief refers to a proposition to which the witness (he who is speaking) adheres, which however may be seen to comprise two initially distinct forms: that which reflects internal truth, the individual’s loyalty to his own soul, and that which agrees with commonly understood norms. The third kind of belief is seen from the judge’s perspective, from the one who listens and tries to see. It concerns the process by which he arrives at a probable certitude regarding the idea that he is confronted with the truth. Thus the construction of judiciary truth supposes the creation of distinctions and of procedures which allow the reconstruction of that which occurred from the unequal vantage points of certainty which these different modes of believing contain.