cannot reveal to us the true nature of things, the core of reality: it is limited to the outside, to mere appearance. Knowledge in the scientific sense is possible, only where there is sense-perception, in the domain of space and time: concepts without percepts are empty. And within the field of nature, in the realm of physical and mental phenomena, inexorable law reigns: every physical process, and every human act conceived as part of this process, is absolutely determined, a necessary link in the causal mechanical chain. The tribute to modern science is bravely paid. For the scientific understanding, for our human intelligence with its spatial and temporal categories, nature is a machine in which there is no room for the novel, the unique, and the individual; everything, the self included, is laid out in a serial temporal order, and the entire empirical realm is subject to law.
But there is another side to Kant's philosophy, a door through which entrance can be gained to the world of things in themselves and which is closed against natural science with its sense-experiences and discursive understanding. There is a higher kind of truth than the knowledge of sense-perceived things: truth based on the moral consciousness of man or practical reason, which proclaims us to be free beings, not subject to the mechanism of nature, and gives us an insight into the spiritual world. The moral law within us is a sure guarantee of freedom, an ideal kingdom of ends, immortality, and God: all these are necessary implications of the categorical imperative. We cannot penetrate reality through the husk of sense-experience; the scientific manipulation of sensations can never carry us beyond the outside, into the heart of things where freedom and purpose reigns. Nor can immediate experience reveal to us the promised land: the closer we get to immediacy, the nearer we get to chaos and the farther from truth: percepts without concepts are blind. Neither can we ever intuit or envisage the real; that would mean a face to face greeting of the thing in itself, a power of intellectual intuition which we do not possess. "Freedom, God, and immortality transcend all sense-perception; they are not objects of knowledge and science, but objects of necessary thought and faith."
