is united, in a short time; so that nothing will be left to future
generations except the task of illustrating and applying it
didactically. For this science is nothing more than the inventory of
all that is given us by pure reason, systematically arranged.
Nothing can escape our notice; for what reason produces from itself
cannot lie concealed, but must be brought to the light by reason
itself, so soon as we have discovered the common principle of the
ideas we seek. The perfect unity of this kind of cognitions, which are
based upon pure conceptions, and uninfluenced by any empirical
element, or any peculiar intuition leading to determinate
experience, renders this completeness not only practicable, but also
necessary.
Tecum habita, et noris quam sit tibi curta supellex.*
*Persius. [Satirae iv. 52. "Dwell with yourself, and you will know
how short your household stuff is."
Such a system of pure speculative reason I hope to be able to
publish under the title of Metaphysic of Nature. The content of this
work (which will not be half so long) will be very much richer than
that of the present Critique, which has to discover the sources of
this cognition and expose the conditions of its possibility, and at
the same time to clear and level a fit foundation for the scientific
edifice. In the present work, I look for the patient hearing and the
impartiality of a judge; in the other, for the good-will and
assistance of a co-labourer. For, however complete the list of
principles for this system may be in the Critique, the correctness
of the system requires that no deduced conceptions should be absent.
These cannot be presented a priori, but must be gradually
discovered; and, while the synthesis of conceptions has been fully
exhausted in the Critique, it is necessary that, in the proposed work,
the same should be the case with their analysis. But this will be
rather an amusement than a labour.
PREFACE TO THE SECOND EDITION, 1787
Whether the treatment of that portion of our knowledge which lies
within the province of pure reason advances with that undeviating
certainty which characterizes the progress of science, we shall be
at no loss to determine. If we find those who are engaged in
metaphysical pursuits, unable to come to an understanding as to the
method which they ought to follow; if we find them, after the most
elaborate preparations, invariably brought to a stand before the
goal is reached, and compelled to retrace their steps and strike
into fresh paths, we may then feel quite sure that they are far from
having attained to the certainty of scientific progress and may rather
be said to be merely groping about in the dark. In these circumstances
we shall render an important service to reason if we succeed in simply
indicating the path along which it must travel, in order to arrive
at any results- even if it should be found necessary to abandon many
