But what is this unknown something with which the Reason collides when inspired by its paradoxical passion, with the result of unsettling even man's knowledge of himself? It is the Unknown. It is not a human being, insofar as we know what man is; not is it any other known thing. So let us call this unknown something: God. It is nothing more than a name we assign to it. The idea of demonstrating that this unknown something (God) exists could scarcely suggest itself to the Reason. For if God does not exist it would of course be impossible to prove it; and if he does exist it would be folly to attempt it. For at the very outset, in beginning my proof, I will have presupposed it, not as doubtful but as certain (a presupposition is never doubtful, for the very reason that it is a presupposition), since otherwise I would not begin, readily understanding that the whole would be impossible if he did not exist. But if when I speak of proving God's existence I mean that I propose to prove that the Unknown, which exists, is God, then I express myself unfortunately. For in that case I do not prove anything, least of all an existence, but merely develop the content of a conception. Generally speaking, it is a difficult matter to prove that anything exists; and what is still worse for the intrepid souls who undertake the venture, the difficulty is such that fame scarcely awaits those who concern themselves with it. The entire demonstration always turns into something very different from what it assumes to be, and becomes an additional development of the consequences that flow from [our] having assumed that the object in question exists. Thus I always reason from existence, not toward existence, whether I move in the sphere of palpable sensible fact or in the realm of thought. I do no ...