any such attempt, I confine myself to the examination of reason alone
and its pure thought; and I do not need to seek far for the
sum-total of its cognition, because it has its seat in my own mind.
Besides, common logic presents me with a complete and systematic
catalogue of all the simple operations of reason; and it is my task
to answer the question how far reason can go, without the material
presented and the aid furnished by experience.

So much for the completeness and thoroughness necessary in the
execution of the present task. The aims set before us are not
arbitrarily proposed, but are imposed upon us by the nature of
cognition itself.

The above remarks relate to the matter of our critical inquiry. As
regards the form, there are two indispensable conditions, which any
one who undertakes so difficult a task as that of a critique of pure
reason, is bound to fulfil. These conditions are certitude and
clearness.

As regards certitude, I have fully convinced myself that, in this
sphere of thought, opinion is perfectly inadmissible, and that
everything which bears the least semblance of an hypothesis must be
excluded, as of no value in such discussions. For it is a necessary
condition of every cognition that is to be established upon a priori
grounds that it shall be held to be absolutely necessary; much more
is this the case with an attempt to determine all pure a priori
cognition, and to furnish the standard--and consequently an example--
of all apodeictic (philosophical) certitude. Whether I have
succeeded in what I professed to do, it is for the reader to
determine; it is the author's business merely to adduce grounds and