So the concept of a noumenon is only a boundary concept, whose role is to limit the pretensions of sensibility; which means that its only use is the negative one. But it’s not a sheer human invention; it is bound up with the limitation of sensibility, though it can’t affirm anything positive beyond the domain of sensibility.
Thus: we can properly divide concepts into •sensible concepts and •intellectual ones,but we cannot properly divide objects into •phenomena and •noumena, or divide the world into a •world of the senses and a •world of the understanding, with these terms understood in a positive sense. For no object can be picked out for the intellectual concepts, and consequently we can’t pass them off as objectively valid. . . .
老三篇不但正规军要学，游击队也要学。俺在网上找了老半天，原来康德的“物自体”就是 “thing in itself”。
The positive value of the critical principles of pure reason in relation to the conception of God and of the simple nature of the soul, admits of a similar exemplification; but on this point I shall not dwell. I cannot even make the assumption—as the practical interests of morality require—of God, freedom, and immortality, if I do not deprive speculative reason of its pretensions to transcendent insight. For to arrive at these, it must make use of principles which, in fact, extend only to the objects of possible experience, and which cannot be applied to objects beyond this sphere without converting them into phenomena, and thus rendering the practical extension of pure reason impossible. I must, therefore, abolish knowledge, to make room for belief. The dogmatism of metaphysics, that is, the presumption that it is possible to advance in metaphysics without previous criticism, is the true source of the unbelief (always dogmatic) which militates against morality。
