from the fact that both constitute one whole, the intellect itself creates that order, and exists only for things, while they, on the other hand, exist only for it. But even apart from the deep insight, which only the Kantian philosophy gives, the inadmissibility of the assumption of absolute realism which is so obstinately clung to may be directly shown, or at least made capable of being felt, by the simple exhibition of its meaning in the light of such considerations as the following. According to realism, the world is supposed to exist, as we know it, independently of this knowledge. Let us once, then, remove all percipient beings from it, and leave only unorganised and vegetable nature. Rock, tree, and brook are there, and the blue heaven; sun, moon, and stars light this world, as before; yet certainly in vain, for there is no eye to see it. Let us now in addition place in it a percipient being. Now that world presents itself _again_ in his brain, and repeats itself within it precisely as it was formerly without it. Thus to the _first_ world a _second_ has been added, which, although completely separated from it, resembles it to a nicety. And now the _subjective_ world of this perception is precisely so constituted in _subjective_, known space as the _objective_ world in _objective_, infinite space. But the subjective world has this advantage over the objective, the knowledge that that space, outside there, is infinite; indeed it can also give beforehand most minutely and accurately the whole constitution or necessary properties of all relations which are possible, though not yet actual, in that space, and does not require to examine them. It can tell just as much with regard to the course of time, and also with regard to the relation of cause and effect which governs the changes in that external world. I think all this, when closely considered, turns out absurd enough, and hence leads to the conviction that that absolute objective world outside the head, independent of it and prior to all knowledge, which at first we imagined ourselves to conceive, is really no other than the second, the world which is known _subjectively_, the world of idea, as which alone we are actually able to conceive it. Thus of its own accord the assumption forces itself upon us, that the world, as we know it, exists also only for our knowledge, therefore in the _idea_ alone, and not a second time outside of it.(12) In accordance, then, with this assumption, the thing in itself, _i.e._, that which exists independently of our knowledge and of every knowledge, is to be regarded as something completely different from the _idea_ and all its attributes, thus from objectivity in general. What this is will be the subject of our second book.