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INTRODUCTION

can not be deduced from a higher principle, the relation to which might demonstrate its certainty. Since, nevertheless, it is to be the basis of all certainty, it must be certain in itself, through itself, and for the sake of itself, All other propositions will be certain, because it can be shown that they are in some respect related to it, but this one must be certain merely because it is related to itself. All other propositions will only have a mediated certainty derived from it, but itself must have immediate certainty. Upon it all knowledge is grounded, without it no knowledge were indeed possible; but itself has its ground in no other knowledge, being, on the contrary, itself the ground of all knowledge. This fundamental principle is absolutely certain; that is, it is certain because it is certain. You can not inquire after its ground without contradiction. It is the ground of all certainty; that is, every thing which is certain is certain, because this fundamental principle is certain, and nothing is certain if it is not certain. It is the ground of all knowledge; that is, you know what it asserts, simply because you know any thing at all; you know it immediately when you know any thing at all. It accompanies all knowledge, is contained in all knowledge, and is presupposed by all knowledge. The science of knowledge, in so far as it is a science, and is to consist of more than its fundamental principle—which seems necessary, since it is to furnish the fundamental principles of all sciences—must have a systematic form. It is evident that it can not derive