but may derive them from practical sources.]

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.

Thus, while it may be no very difficult task to bequeath a legacy to
posterity, in the shape of a system of metaphysics constructed in
accordance with the Critique of Pure Reason, still the value of such
a bequest is not to be depreciated. It will render an important
service to reason, by substituting the certainty of scientific
method for that random groping after results without the guidance of
principles, which has hitherto characterized the pursuit of
metaphysical studies. It will render an important service to the
inquiring mind of youth, by leading the student to apply his powers
to the cultivation of genuine science, instead of wasting them, as
at present, on speculations which can never lead to any result, or
on the idle attempt to invent new ideas and opinions. But, above all,