be understood that a truthful answer may be obtained. _History_ must be known in order to obtain the truth of _philosophy._ [Sidenote: _Historical quality of the culture required in the philosopher._] This demand is usually expressed in the formula that the philosopher must be cultured, though it is not clear what is the quality of this culture that is said to be requisite. Some, especially in our own days, would wish the philosopher to be a physiologist, a physicist, a mathematician, that is, that his brain should be full of abstractions, which are certainly not useless (everything is worth knowing, even the triviality of girls, for even that is a part of life and of reality), but which are in no direct relation to that form of knowledge which must be the condition of philosophy. This form of knowledge is, on the contrary, history; or, as it is said (with an _a potiori_ intention), the history of philosophy, which of necessity as the history of a moment of the spirit, includes all history in itself, as we have shown above, when criticizing the divisions of history. That is to say, it is necessary to know the meaning of the problems of our own time, and this implies knowing also those of the past, in order not to take the former for the latter and so cause inextricable confusion. And to the extent that they can be of use according to the requirements of the problem, we must know also the natural, physical, and mathematical sciences. But we must _not_ know them _as stick_ and develop them as such, but rather _as historical knowledge_ concerning the state of the natural sciences, of physics, and of mathematics, in order to understand the problems that they help to raise for philosophy. [Sidenote: _Apparent objections._]