In regard to the ideality of space, Schopenhauer says, "The clearest and most simple proof of the ideality of space is that we can never get it out of our thoughts, as we might anything else. We can fancy space as having no longer anything to fill it, we can imagine that everything within it has disappeared, we can represent it as being, between the fixed stars, an absolute void, but space itself we can never get rid of; whatever we do, however we turn, there it is in endless expansion. This fact certainly proves that space is a part of our intellect; or, in other words, that it is the woof of the tissue upon which the different objects of the exterior world apply themselves. As soon as I think of an object, space appears with it and accompanies every movement, every turn and _détour_ of my thought, as faithfully as the spectacles on my nose accompany every movement, every turn and _détour_ of my person, or just in the same manner as the shadow accompanies the body. If I notice that a thing accompanies me everywhere, and under all circumstances, I naturally conclude that it is in some way connected with me; as if, for instance, wherever I went I noticed a particular odor from which I could not escape. Space is precisely the same; whatever I think of, what ever I imagine, space comes first and yields its place to nothing. It must, therefore, be an integral part of my understanding, and its ideality in consequence must extend to everything that is thinkable." Space and time being but the empty framework of phenomenal existence, something must fill them, and that something is causality, which, according to Schopenhauer, is synonymous with action and matter. Into these abstract regions, however, it is unnecessary to follow him any further. Suffice it to say that having shown in this way that one of the two zones of which the world is formed is but an effect of the perceptions, he passes therefrom to the world as it is. Now there were many paths which might or might not have led him to the unravelment of the great secret which Kant gave up in despair, there were many ways which seemed to tend to a direct solution of the Sphinx's riddle, but the course which he chose, and which brought him nearer to the proper answer than any other system of which the world yet knows, may be fairly said to have been inspired by the spirit of truth, and as an inspiration given first to him of all men.