Whence does the human mind derive these ideal types, these concepts or definitions of the nature of things? It derives them from actually experienced reality by abstraction, comparison, generalization, and reflection on the data of its experience.(163) Hence it follows that the ontological truth of things is not known by the mind antecedently to the formation of the mental type. It is, of course, in the things antecedently to any judgment we form about the things; and the logical truth of our judgments is dependent on it, for logical truth is the conformity of our judgments with the real nature of things. But antecedently to all exercise of human thought, antecedently to our conception of the nature of a thing, the thing has not for us _formal_ or _actual_ ontological truth: it has only fundamental or _potential_ ontological truth. If in this condition reality had actual ontological truth for us, there would be no ground for our distinguishing mentally between the reality and the truth of things; whereas the existence of this mental or logical distinction is undeniable. The concept of reality is the concept of something absolute; the concept of ontological truth is the concept of something relative, not of an absolute but of a relative property of being. But if for the human mind the ontological truth of things is—at least proximately, immediately, and in the first place—their conformity with the abstract concepts of essences or natures, concepts derived by the mind from an analysis of its experience, how can this ontological truth be one for all men, or immutable and necessary? For, since men form different and divergent and conflicting conceptions as to the natures of things, and so have different views and standards of truth for things, ontological truth would seem, according to the exposition just outlined, to be not one but manifold, not immutable but variable: consequences which surely cannot be admitted? The answer to this difficulty will lead us to a deeper and more fundamental conception of what ontological truth really is.