We derive all our knowledge, through external and internal sense perception, from the domain of actually existing things, these things including our own selves and our own minds. We form, from the data of sense-consciousness, by an intellectual process proper, mental representations of an abstract and universal character, which reveal to us partial aspects and phases of the natures of things. We have no intuitive intellectual insight into these natures. It is only by abstracting their various aspects, by comparing these in judgments, and reaching still further aspects by inferences, that we progress in our knowledge of things—gradually, step by step, _discursivé_, _discurrendo_. All this implies reflection on, and comparison of, our own ideas, our mental views of things. It involves the processes of defining and classifying, affirming and denying, abstracting and generalizing, analysing and synthesizing, comparing and relating in a variety of ways the objects grasped by our thought. Now in all these complex functions, by which alone the mind can _interpret rationally_ what is given to it, by which alone, in other words, it can know reality, the mind necessarily and inevitably forms for itself (and expresses in intelligible language) a series of concepts which have for their objects only the _modes_ in which, and the _relations_ by means of which, it makes such gradual progress in its interpretation of what is given to it, in its knowledge of the real. These concepts are called _secundae intentiones mentis_—concepts of the second order, so to speak. And their objects, the modes and mutual relations of our _primae intentiones_ or direct concepts, are called _entia rationis_—logical entities. For example, _abstractness_ is a mode which affects not the reality which we apprehend intellectually, but the concept by which we apprehend it. So, too, is the _universality_ of a concept, its communicability or applicability to an indefinite multitude of similar realities—the “_intentio universalitatis_,” as it is called—a mode of concept, not of the realities represented by the latter. So, likewise, is the _absence_ of other reality than that represented by the concept, the _relative nothingness or non-being_ by contrast with which the concept is realized as positive; and the _absolute nothingness or non-being_ which is the logical correlative of the concept of being; and the static, unchanging self-identity of the object as conceived in the abstract.(64) These are not modes of reality _as it is_ but _as it is conceived_. Again, the manifold logical relations which we establish between our concepts—relations of (extensive or intensive) identity or distinction, inclusion or inherence, etc.—are logical entities, _entia rationis_: relations of genus, species, differentia, proprium, accidens; the affirmative or negative relation between predicate and subject in judgment;(65) the mutual relations of antecedent and consequent in inference.