From all this it also appears, which I consider expedient to remark here, that a philosophy, in order to be a science, need not be _universally valid_, as some philosophers seem to assume. These philosophers demand the impossible. What does it mean: a philosophy is really universally valid? Who, then, are all these for whom it is to be valid? I suppose not to every one who has a human face, for then it would also have to be valid for children and for the common man, for whom thinking is never object, but always the means for his real purpose. Universally valid, then, for the philosophers? But who, then, are the philosophers? I hope not all those who have received the degree of doctor from some philosophical faculty, or who have printed something which they call philosophical, or who, perhaps, are themselves members of some philosophical faculty? Indeed, how shall we even have a fixed conception of the philosopher, unless we have first a fixed conception of philosophy—i. e. unless we first possess that fixed philosophy? It is quite certain that all those who believe themselves possessed of philosophy, as a science, will deny to all those who do not recognize their philosophy the name of philosopher, and hence will make the acknowledgment of their philosophy the criterion of a philosopher. This they must do, if they will proceed logically, for there is only one philosophy. The author of the Science of Knowledge, for instance, has long ago stated that he is of this opinion in regard to his system—not in so far as it is an _individual representation_ of that system, but in so far as it is a system of _transcendental idealism_—and he hesitates not a moment to repeat this assertion. But does not this lead us into an evident circle? Every one will then say, “My philosophy is universally valid for all philosophers;” and will say so with full right if he only be himself convinced, though no other mortal being should accept his doctrine; “for,” he will add, “he who does not recognize it as valid is no philosopher.” Concerning this point, I hold the following: If there be but one man who is fully and at all times equally convinced of his philosophy, who is in complete harmony with himself in this his philosophy, whose free judgment in philosophizing agrees perfectly with the judgment daily life forces upon him, then in this one man philosophy has fulfilled its purpose and completed its circle; for it has put him down again at the very same point from which he started with all mankind; and henceforth philosophy as a science really exists, though no other man else should comprehend and accept it; nay, though that one man might not even know how to teach it to others.