The transition from the preliminary stages of the subjective deduction to the objective deduction may be made by further analysis either of the objective unity of empirical concepts or of the subjective unity of empirical self-consciousness. It is the former line which the argument of the first edition follows. Kant is asking what is meant by an object corresponding to our representations,[890] and answers by his objective deduction. He substitutes the empirical for the transcendental object,[891] and in so doing propounds one of the central and most revolutionary tenets of the Critical philosophy. Existence takes a threefold, not a merely dual form. Besides representations and things in themselves, there exist the objects of our representations--the extended world of ordinary experience and of science. Such a threefold distinction is prefigured in the Leibnizian metaphysics, and is more or less native to every philosophy that is genuinely speculative. Kant himself claims Plato as his philosophical progenitor. The originality is not in the bare thesis, but in the fruitful, tenacious, and consistent manner in which it is developed through detailed analysis of our actual experience. In its first stages the argument largely coincides with the argument of the paragraphs which deal with the transcendental object. When we examine the objective, we find that the primary characteristic distinguishing it from the subjective is that it lays a compulsion upon our minds, constraining us to think about it in a certain way. By an object is meant something which will not allow us to think at haphazard. Cinnabar is an object which constrains us to think it as heavy and red. An object is thus the external source of a necessity to which our thinking has to conform. The two arguments first begin to diverge when Kant sets himself to demonstrate that our consciousness of this external necessity is made possible by categories which originate from within. For this conclusion Kant prepares the way by an analysis of the second main characteristic constitutive of an object, viz. its unity. This unity is of a twofold nature, involving either the category of substance and attribute or the category of cause and effect. The two categories are ultimately inseparable, but lead us to conceive the object in two distinct modes. When we interpret an object through the _a priori_ concept of substance and attribute, we assert that all the contents of our perceptions of it are capable of being regarded as qualities of one and the same identical substance. No one of its qualities can be incongruent with any other, and all of them together, in their unity, must be expressive of its substantial nature.