cartes, in the expression Cogito, Ergo Sum, says, I think, or, I am thinking; he says likewise, I exist, or, I am existing. These affirmations are, in truth, identical. They are contemporaneous, and stand in no relation of subordination. I am thinking is precisely equivalent to I am existing, as it matters not whether we seem to proceed from thinking to existing, or from existing to thinking, for in the one knowledge is given the other: in knowing that I think, I know that I exist, and in knowing that I exist, I know that I think; that is, am conscious of some determinate act manifested by me. The expression, Cogito, Ergo Sum, is, therefore, not an enthymeme with the suppressed major (sumption), what thinks, is: but a simple affirmation of the identity in the sphere of self-consciousness of thought and being.
Nor, in the second place, is the existence of self as the subject of thought inferred from the higher knowledge, every Quality supposes a Substance, but affirmed: self and existence are not first sundered or found apart, and then conjoined through some third knowledge, which is higher, more general, and, therefore, inclusive, but immediately known and affirmed in conjunction, and by the same indivisible act (simplici mentis intuitu), in which we know and affirm the existence of thought. We do not even come to know that self, or a subject of thought exists, through thinking that thought is a quality, for this were virtually to have recourse to the general principle that quality supposes a substance; and besides, to have
