The subject concept in the sense of subjectivity, of egohood, is connected in the most intimate way ontologically with the formal-apophantic category of the subjectum, the ὑποκείμενον, in which at first nothing at all of egohood is present. On the contrary, the ὑποκείμενον is the extant, the disposable. It is because the ego is the subjektum proper or, in Greek, the substance proper, ὑποκείμενον, for the first time explicitly in Kant, even though already prefigured in Descartes and above all in Leibniz, that Hegel can say that the true substance is the subject or the true meaning of substantiality is subjectivity. This principle of the Hegelian philosophy lies in the direct line of development of the problems of modem thought.
What is the most general structure of the ego, or what constitutes egohood? Answer: self-consciousness. All thinking is "I am thinking." The ego is not simply any arbitrary isolated point; it is "I-think." However, it does not perceive itself as a being that would have other determinations beside this one, that it just thinks. Rather the ego knows itself as the ground of its determinations, its comportments, as the ground of its own unity in the multiplicity of these comportments, as the ground of the selfsameness of its own self. All the determinations and comportments of the ego are ego-based. I perceive, I judge, I act. The "I-think," says Kant, must be able to accompany all my representations, that is, every cogitare of cogitata. This statement is not to be taken, however, as though the idea of the ego is present along with every comportment, with every thinking in the broadest sense. Instead, I am conscious of the linkage of all comportments with my ego; that is to say, I am conscious of them in their multiplicity as of my unity, which has its ground in my egohood (as subjectum) as such. It is only on the basis of the "I-think" that any manifold can be given to me. In a summary way, Kant interprets the ego as the "original synthetic unity of apperception." What does this mean? The ego is the original ground of the unity of the manifold of its determinations in this sense, that as ego I have them all together with regard to myself, I keep them together, combine them, from the outset—synthesis. The original ground of unity is what it is, it is this ground as unifying, as synthetic. The combining of the manifold of representations and of what is represented in them must always be thought along with them. The combining is of such a sort that in thinking I am also thinking myself I do not simply apprehend what is thought and represented, I do not just perceive it, but in all thinking I think myself along with it. I do not perceive but apperceive the ego. The original synthetic unity of apperception is the ontological characteristic of the distinctive subject.
From what has been said it becomes clear that with this concept of egohood the formal structure of personality or, as Kant says, personalitas transcendentalis has been gained. What does this term "transcendental" signify? Kant says: "I call transcendental all knowledge which is occupied—not so much with objects as with our mode of knowing objects insofar as this