"Something is thought, therefore there is something that thinks": this is what Descartes' argument amounts to. But this is tantamount to considering our belief in the notion "_substance_" as an "_a priori_" truth:--that there must be something "that thinks" when we think, is merely a formulation of a grammatical custom which sets an agent to every action. In short, a metaphysico-logical postulate is already put forward here--and it is not merely _an ascertainment of fact...._ On Descartes' lines nothing absolutely certain is attained, but only the fact of a very powerful faith. If the proposition be reduced to "Something is thought, therefore there are thoughts," the result is mere tautology; and precisely the one factor which is in question, the "_reality_ of thought," is not touched upon,--so that, in this form, the apparitional character of thought cannot be denied. What Descartes _wanted_ to prove was, that thought not only had _apparent reality,_ but absolute reality. 485. The concept _substance_ is an outcome of the concept _subject,_ and not conversely! If we surrender the concept soul, the subject, the very conditions for the concept "substance" are lacking. _Degrees of Being_ are obtained, but Being is lost. 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.