We have already learned how completely Leibniz reverses this way of regarding reality. According to Locke, reality essentially is; and in its being there is no ground of revelation of itself. It then acts; but these actions, "powers, or qualities," since not flowing from the very being of substance, give no glimpse into its true nature. According to Leibniz, reality acts, and _therefore_ is. Its being is conditioned upon its activity. It is not first there, and secondly acts; but its "being there" is its activity. Since its very substance is activity, it is impossible that it should not manifest its true nature. Its every activity is a revelation of itself. It cannot hide itself as a passive subsistence behind qualities or phenomena. It must break forth into them. On the other hand, since the qualities are not something which merely inhere in an underlying support, but are the various forms or modes of the activity which constitutes reality, they necessarily reveal it. They _are_ its revelations. There is here no need to dwell further on the original dynamic nature of substance; what was said in the way of general exposition suffices. It is only in its relations to Locke's view as just laid down that it now concerns us. In the first place, Leibniz points out that qualities are "abstract," while substance is "concrete." The qualities, from the very fact that they have no self-subsistence, are only relations, while the substance, as that of which they are qualities, or from which they are abstractions, is concrete. It is, Leibniz says, to invert the true order to take qualities or abstract terms as the best known and most easily comprehended, and "concretes" as unknown, and as having the most difficulty about them. "It is abstractions which give birth to almost all our difficulties," and Locke's error here is that he begins with abstractions, and takes them to be most open to intelligence. Locke's second error is separating so completely substance and attribute. "After having distinguished," says Leibniz, "two things in substance, the attributes or predicates, and the common subject of these predicates, it is not to be wondered at that we cannot conceive anything in particular in the subject. This result is necessary, since we have separated all the attributes in which there is anything definite to be conceived. Hence to demand anything more than a mere unknown somewhat in the subject, is to contradict the supposition which was made in making the abstraction and in conceiving separately the subject and its qualities or accidents." We are indeed ignorant of a subject from which abstraction has been made of all defining and characteristic qualities; "but this ignorance results from our demanding a sort of knowledge of which the object does not permit." In short, it is a credit to our knowledge, not an aspersion upon it, that we cannot know that which is thoroughly unreal,--a substance deprived of all attributes.