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of things in themselves, which is independent of the conditions both of our sensibility
and our understanding, but with nature as an object of possible experience; and in this
case the understanding, since it makes experience possible, thereby insists that the
sensuous world is either not an object of experience at all or that it is nature [namely,
the existence of things determined according to universal laws].APPENDIX TO THE PURE SCIENCE
OF NATURE§ 39. Of the System of the Categories. There can be nothing more desirable to a
philosopher than to be able to derive the scattered multiplicity of the concepts or principles
which had occurred to him in concrete use from a principle a priori,and to unite everything
in this way in one cognition. He formerly only believed that those things which remained
after a certain abstraction, and seemed by comparison among one another to constitute a
particular kind of cognitions, were completely collected; but this was only an aggregate.
Now he knows that just so many, neither more nor less, can constitute the kind of cognition,
and perceives the necessity of his division. This constitutes comprehension; and only then
has he attained a system.
To search in our common knowledge for the concepts which do not rest upon
particular experience and yet occur in all knowledge from experience, of which they as
it were constitute the mere form of connection, presupposes neither greater reflection
nor deeper insight than to detect in a language the rules of the actual use of words
generally and thus to collect elements for a grammar (in fact both researches are very
nearly related), even though we are not able to give a reason why each language has
just this and no other formal constitution, and still less why any precise number of such
formal determinations in general, neither more nor less, can be found in it.
Aristotle collected ten pure elementary concepts under the name of categories.*
To these, which are also called “predicaments,” he found himself obliged afterward
to add five post-predicaments,** some of which however (prius, simul,and motus)
are contained in the former; but this rhapsody must be considered (and commended)
as a mere hint for future inquirers, not as an idea developed according to rule; and
hence it has, in the present more advanced state of philosophy, been rejected as quite
useless.
After long reflection on the pure elements of human knowledge (those which
contain nothing empirical), I at last succeeded in distinguishing with certainty and in
separating the pure elementary notions of the sensibility (space and time) from those of
the understanding. Thus the seventh, eighth, and ninth categories had to be excluded
from the old list. And the others were of no service to me because there was no principle
on which the understanding could be exhaustively investigated, and all the functions,
whence its pure concepts arise, determined exhaustively and precisely.
But in order to discover such a principle, I looked about for an act of the under-
standing which comprises all the rest and is distinguished only by various modifications
or phases, in reducing the multiplicity of representation to the unity of thinking in
general. I found this act of the understanding to consist in judging. Here, then, the
labors of the logicians were ready at hand, though not yet quite free from defects; and
with this help I was enabled to exhibit a complete table of the pure functions of the*1. Substantia.2. Qualitas.3. Quantitas.4. Relatio.5. Actio.6. Passio.7. Quando.8. Ubi.9. Situs.- Habitus.
**Oppositum. Prius. Simul. Motus. Habere.
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