 Boethius’s view that the types of potencies and potency based possibilities are sometimes actualized is in agreement with the Aristotelian frequency interpretation of modality. This is another Boethian conception of necessity and possibility. He thought that modal notions can be regarded as tools for expressing temporal or generic frequencies. According to the temporal version, what always is, is by necessity, and what never is, is impossible. Possibility is interpreted as expressing what is at least sometimes actual. Correspondingly, a generic property of a species is possible only if it is exemplified at least in one member of that species (In Periherm. I, 120–121, 200–201; II, 237).