Since our sensual experience does not reveal to us the world as it is in itself, but only as it is for us—as it appears to us—thanks to the peculiar constitution of our faculties of knowledge, so the world as it is in itself must be different to that which appears to us. Consequently Kant distinguishes between the world of phenomena, of appearances, and the world of things in themselves, the "noumena," or the intelligible world. This latter is for us unknowable, it lies outside of cur experience, so that there is no need to deal with it; one might simply take it as a method of designating the fact that our knowledge of the world is always limited by the nature of our intellectual faculties, is always relative: that for us there can only be relative and no absolute truths, not a final and complete knowledge, but an endless process of knowing.
But Kant was not content with that. He felt an unquenchable longing to get a glimpse into that unknown and inexplorable world of things in themselves, in order to acquire at least a notion of it.
And indeed he got so far as to say quite distinct things about it. The way to this he saw in the critique of our powers of thought. These latter, by separating from experience that which comes from the senses, must arrive at the point of describing the forms of knowledge and perception as they originally and á priori, previous to all experience, are contained in our "feelings." In this manner he discovered the ideality of time and space. According to him, these are not conceptions which are won from experience, but simply the forms of our conception of the world, which are embedded in our faculties of knowledge. Only under the form of conceptions in time and space can we recognise the world. But outside of our faculties of knowledge there is no space and no time. Thus Kant got so far as to say about the world of things in themselves, that completely unknowable world, something very distinct, namely, that it is timeless and spaceless.
Without doubt this logical development is one of the most daring achievements of the human mind. That
