Because both alike are hampered by a contradiction within themselves. This contradiction becomes manifest in the fact that such a world as would be yielded by the concept of _substans_ would be so constituted that in it the fact “concept,” _i.e._ the fact that a world exists as idea, would be bound to remain an eternally insoluble problem. This necessarily results from the following considerations:-- If there is any _substans_ lying at the foundation of things, it must be a “constant in itself”; as such, however, it must be something possessing no possibility whatever of entering into relations with other things, in any kind of way. If it cannot do this, neither can it become perceptible to sense. If it does not become perceptible to sense, it cannot become a content of consciousness. Here it may be said: “But it is not _substans_ itself, but its expressions, _i.e._ things, in so far as they are properties, functions, that enter into relations, whether with other things or with the organs of sense of living beings.” But from this we could never get anything else but a summation of disconnected sense-impressions. The thread, so to speak, needed to string the sense-impressions together into a complete, coherent, mental representation would be missing. Everything, so far as it exists for me as a concept, would have to be the expression precisely of a _substans_ lying at its foundation. But to possess a conscious mental representation of this as an unconditioned constant is a contradiction in itself. Hence the fact that there are concepts, _i.e._ that a world as such exists, _i.e._ that there is a world at all, is a direct contradiction of the idea of a _substans_ in virtue of which things are supposed to have existence. With the admission of this idea, every possibility of understanding how such a thing as a content of consciousness ever could come to be, is wholly excluded. In point of fact, all life, within the boundaries of materialism and idealism, exhausts itself in fruitless attempts to furnish more or less ingenious explanations to account for the connection between the physical and the psychical. Hence the perpetual game of see-saw between both, and the utter inadequacy of either to the genuine thinker, however much ability may be displayed within the limits of the position chosen. All becomes valueless, because the outcome of a presupposition that is a standing contradiction of itself. And now, how stands it here with the view of the world from which _substans_ is absent? As already said: Where the idea of _substans_ is torn out of the play of world-events, nothing remains but a world of pure relation-values wherein the one thing constant is the constancy of the relations.