Criticism of "reality": what does a "plus or minus of reality" lead to, the gradation of Being in which we believe?
The degree of our feeling of life and power (the logic and relationship of past life) presents us with the measure of "Being," "reality," "non-appearance."
Subject i this is the term we apply to our belief in an entity underlying all the different moments of the most intense sensations of reality; we regard this belief as the effect of a cause,—and we believe in our belief to such an extent that, on its account alone, we imagine "truth," "reality," "substantiality."—a "Subject" is the fiction which would fain make us believe that several similar states were the effect of one substratum: but we it was who first created the "similarity" of these states; the similising and adjusting of them is the fact—not their similarity (on the contrary, this ought rather to be denied).
486.
One would have to know what Being is, in order to be able to decide whether this or that is real (for instance, "the facts of consciousness"); it would also be necessary to know what certainty and knowledge are, and so forth.—But, as we do not know these things, a criticism of the faculty of knowledge is nonsensical: how is it possible for an instrument to criticise itself, when it is itself that exercises the critical faculty. It cannot even define itself!
487.
Should not all philosophy ultimately disclose the first principles on which the reasoning processes depend?—that is to say, our belief in the "ego" as a substance, as the only reality according to which, alone, we are able to ascribe reality to things? The oldest realism at length comes to light, simultaneously with man's recognition of the fact that his whole religious history is no more than a history of soul-superstitions. Here there is a barrier; our very thinking, itself, involves that belief (with its distinctions—substance, accident, action, agent, etc.); to abandon it would mean to cease from being able to think.
But that a belief, however useful it may be for the preservation of a species, has nothing to do with the truth, may be seen from the fact that we must believe in time, space, and motion, without feeling ourselves compelled to regard them as absolute realities.
488.