Whether it is the one he is speaking of,8 the true,9 or the good," St. Thomas is always concerned to point out the basic identity between being and the transcendentals. Being and one, for example, do not signify different entities or natures, but the same nature: unum autem et ens non diversas naturas sed unam significant. The transcendentals, in short, do not constitute separate realities; it is the one reality which they express, namely being. Nevertheless, while really (in re) identical with being, the transcendentals are not conceptually identical with it. After all, "to be one" or "to be good" are not simple tautologies; in both something is added to "to be," something said which is not said by "to be" alone. There is, then, some ground of distinction between being and the transcendentals; but since the difference is obviously not in reality, it can only be in the mind, a distinction of reason. In the case of transcendental one the distinction (or addition) consists, as we shall see, of a negation, whereas in the true and the good it is a relation. St. Thomas makes this point when he writes:
To being, the first conception of the intellect, one adds what is merely conceptual [rationis tantum] - a negation; for, one means undivided being. But true and good, which are predicated positively, cannot add anything except a relation which is merely conceptual.11
a) The distinction in question must, however, be further defined. A distinction is real when it exists independently of the mind, when it pertains to elements of reality of which one is not actually the other(s). A distinction of reason, on the other hand, also called logical, exists only in the mind, i.e. only as product of a mental activity. It occurs, therefore, when the mind forms different concepts of what in itself is simply one. But a distinction of reason may have a foundation in reality; in which case it is said to be a virtual distinction (Scholastically: rationis ratiocinatae). If it lacks this foundation it is a construct of the mind pure and simple, a purely logical or verbal distinction (rationis ratiocinantis). The distinction of the transcendentals from being, while not real, has a foundation in reality; it is therefore virtual.
However, the virtual distinction itself admits of discrimination. For, the concepts distinguished may be such that one contains the other(s) only potentially (as genus the species), which makes for a major virtual distinction. Or, one concept contains the other(s) actually but not explicitly (as analogue the analogated perfections, and being the transcendental properties), in which circumstances we have to do with a minor virtual distinction - the answer to the question in point, the nature of the distinction between being and its transcendental properties.
b) A further clarification concerns specifically the transcendental true and good, lest they be confused with the relations which go with them. Though necessarily implied in each, the relation is not the transcendental. Basically, the true and the good designate being so far as it has reference respectively to the cognitive and the appetitive powers, which means so far as it is determined by the relation to these powers. Thus, what is signified by the transcendental true and good is the reality of being itself, but signified as grounding the order of knowledge and of appetition.