  Porphyry’s list of predicables not only occasioned the question of its relation to transcendental predicates, but also supplied a model to express the relation of ‘being’ to the other transcendentals as the relation between a subject and its properties (propria). Although the transcendentals are co-extensive, they differ conceptually. The privileged model to express this relationship was the predication of a property (proprium) of a subject, which is defined by Porphyry with two characteristics: on the one hand, properties are convertible with the subject, on the other hand, they are outside the essence of the subject. The first characteristic was of great convenience, since it offers the possibility to combine the convertibility of the transcendentals with the basic task of science: to demonstrate the existence of properties that belong per se to its subject and are hence convertible with it. By explaining the relation between ‘being’ and the other transcendental predicates as the relation between a subject and its properties, the doctrine of the transcendentals gives flesh to the science of ‘being’ called metaphysics, the core of which is the demonstration that ‘being’ has convertible properties, like ‘one’, ‘true’, and ‘good’. The second characteristic of a property was more problematic at the transcendental level, for it implies the recognition that the transcendentals, as really distinct from being, are nothing. Most theoreticians of the transcendentals, therefore, denied the application of this second characteristic to the transcendental level and held that a transcendental property differs from being only conceptually (secundum rationem). Duns Scotus and the tradition he established, however, accepted a real distinction in the sense of a formal distinction (for this term, cf. infra) in the relation between ‘being’ and its transcendental properties.