not ventured on the experiment--contrary to the senses but still just--
of looking for the observed movements not in the heavenly bodies,
but in the spectator. In this Preface I treat the new metaphysical
method as a hypothesis with the view of rendering apparent the first
attempts at such a change of method, which are always hypothetical.
But in the Critique itself it will be demonstrated, not
hypothetically, but apodeictically, from the nature of our
representations of space and time, and from the elementary conceptions
of the understanding.]

This attempt to introduce a complete revolution in the procedure
of metaphysics, after the example of the geometricians and natural
philosophers, constitutes the aim of the Critique of Pure
Speculative Reason. It is a treatise on the method to be followed,
not a system of the science itself. But, at the same time, it marks
out and defines both the external boundaries and the internal structure
of this science. For pure speculative reason has this peculiarity,
that, in choosing the various objects of thought, it is able to define
the limits of its own faculties, and even to give a complete
enumeration of the possible modes of proposing problems to itself,
and thus to sketch out the entire system of metaphysics. For, on the
one hand, in cognition a priori, nothing must be attributed to the
objects but what the thinking subject derives from itself; and, on
the other hand, reason is, in regard to the principles of cognition,
a perfectly distinct, independent unity, in which, as in an organized
body, every member exists for the sake of the others, and all for the
sake of each, so that no principle can be viewed, with safety, in one
relationship, unless it is, at the same time, viewed in relation to
the total use of pure reason. Hence, too, metaphysics has this
singular advantage--an advantage which falls to the lot of no other