But, leaving the nature of propositions, and different ways of predication to be considered more at large in another place, let us proceed now to inquire concerning our knowledge of the EXISTANCE OF THINGS, and how we come by it. I say, then, that we have the knowledge of OUR OWN existence by intuition; of the existence of GOD by demonstration; and of OTHER THINGS by sensation. 3. Our Knowledge of our own Existence is Intuitive. As for OUR OWN EXISTENCE, we perceive it so plainly and so certainly, that it neither needs nor is capable of any proof for nothing can be more evident to us than our own existence. I think, I reason, I feel pleasure and pain: can any of these be more evident to me than my own existence? If I doubt of all other things, that very doubt makes me perceive my own existence, and will not suffer me to doubt of that. For if I know I feel pain, it is evident I have as certain perception of my own existence, as of the existence of the pain I feel: or if I know I doubt, I have as certain perception of the existence of the thing doubting, as of that thought which I CALL DOUBT. Experience then convinces us, that we have an INTUITIVE KNOWLEDGE of our own existence, and an internal infallible perception that we are. In every act of sensation, reasoning, or thinking, we are conscious to ourselves of our own being; and, in this matter, come not short of the highest degree of certainty. CHAPTER X. OF OUR KNOWLEDGE OF THE EXISTENCE OF A GOD. 1. We are capable of knowing certainly that there is a God. THOUGH God has given us no innate ideas of himself; though he has stamped no original characters on our minds, wherein we may read his being; yet having furnished us with those faculties our minds are endowed with, he hath not left himself without witness: since we have sense, perception, and reason, and cannot want a clear proof of him, as long as we carry OURSELVES about us. Nor can we justly complain of our ignorance in this great point; since he has so plentifully provided us with the means to discover and know him; so far as is necessary to the end of our being, and the great concernment of our happiness. But, though this be the most obvious truth that reason discovers, and though its evidence be (if I mistake not) equal to mathematical certainty: yet it requires thought and attention; and the mind must apply itself to a regular deduction of it from some part of our intuitive knowledge, or else we shall be as uncertain and ignorant of this as of other propositions, which are in themselves capable of clear demonstration. To show, therefore, that we are capable of KNOWING, i.e. BEING CERTAIN that there is a God, and HOW WE MAY COME BY this certainty, I think we need go no further than OURSELVES, and that undoubted knowledge we have of our own existence. 2. For Man knows that he himself exists.