 As happens very often in the case of medieval authors, the salient features of Paul of Venice’s general view about potency and act (and possible and real as well) are partly determined by the concrete applications that the theory pursues. The specific areas that the theory is called to cover are: (1) the (meta)physical explanation of the nature and modalities of change and coming to be; (2) the determination of the form of existence of universals with respect to singulars; and (3) the explanation of the process of creation. Paul proceeds by divisions that allow him to order this subject according to a tree-like scheme that follows in some ways that adopted by Porphyry in the chapter on species in his Isagoge. We can leave out the minor divisions to concentrate on the main one only. At the basis of Paul’s doctrine of act and potency we find a distinction between potency considerd as a disposition to exist, or logical possibility (the potentia ad esse), and potency as a disposition (proper to something which already exists) to perform or achieve something or to undergo a change, or natural possibility (the potentia in esse) (see SN, pars vi, ch. 7, fol. 97ra). This distinction should allow him to separate the logical-theoretical sphere (the potentia ad esse) from the physical one (the potentia in esse). The example chosen to illustrate the nature of the potentia ad esse, that is, the birth of the Antichrist, manifests, however, an internal ambiguity in his doctrine. The existence of the Antichrist, in fact, is a possible not in the sense of non-impossible (i.e., something not contradictory in itself) but in the sense of that which, while not yet real, is however infallibly destined to become real.