c. Since the universal as such, the idea of species, is, according to Locke, merely a product of our mind, which is not itself objective, but relates merely to objects which are germane to it, and from which the particular of qualities, conditions, time, place, etc., are separated, Locke distinguishes essences into real essences and nominal essences; the former of these express the true essence of things, while species on the other hand are mere nominal essences which no doubt express something which is present in the objects, but which do not exhaust these objects. They serve to distinguish species for our knowledge, but the real essence of nature we do not know.[229] Locke gives good reasons for species being nothing in themselves—for their not being in nature, or absolutely determined—instancing in exemplification the production of monstrosities (Bk. III. chap. iii. § 17): were species absolute no monster would be born. But he overlooks the fact that since it pertains to species to exist, it thereby likewise enters into relationship with other determinations; thus that is the sphere in which individual things operate upon one another, and may hence be detrimental to the existence of the species. Locke thus argues just as one would who wished to prove that the good does not exist in itself, because there are likewise evil men, that the circle does not exist absolutely in nature, because the circumference of a tree, for example, represents a very irregular circle, or because I draw a circle badly. Nature just signifies the lack of power to be perfectly adequate to the Notion; it is only in spirit that the Notion has its true existence. To say that species are nothing in themselves, that the universal is not the essential reality of nature, that its implicit existence is not the object of thought, is tantamount to saying that we do not know real existence: it is the same litany which has since been so constantly repeated that we are tired of listening to it: Das Innere der Natur kennt kein erschaffener Geist, and which goes on until we have perceived that Being-for-another, perception, is not implicit; a point of view which has not made its way to the positive position that the implicit is the universal. Locke is far back in the nature of knowledge, further back than Plato, because of his insistence on Being-for-another. It is further noteworthy that from the sound understanding Locke argues (Vol. III. Bk. IV. chap. vii. § 8-11) against universal propositions or axioms such as that A = A, _i.e._ if anything is A it cannot be B. He says they are superfluous, of very little use or of no use at all, for nobody yet has built up a science on a proposition which asserts a contradiction. From such the true may be proved as easily as the false; they are tautological. What Locke has further achieved in respect of education, toleration, natural rights or universal state-right, does not concern us here, but has to do with general culture.