834 IMMANUELKANT
them. There is, therefore, not a continual progress and approximation towards these
sciences, and there is not, as it were, any point or line of contact. Natural science will
never reveal to us the internal constitution of things, which, though not appearance, yet
can serve as the ultimate ground for explaining appearances. Nor does that science
require this for its physical explanations. Nay, even if such grounds should be offered
from other sources (for instance, the influence of immaterial beings), they must be
rejected and not used in the progress of its explanations. For these explanations must
only be grounded upon that which as an object of sense can belong to experience, and
be brought into connection with our actual perceptions and empirical laws.
But metaphysics leads us towards bounds in the dialectical attempts of pure
reason (not undertaken arbitrarily or wantonly, but stimulated thereto by the nature of
reason itself). And the transcendental Ideas, as they do not admit of evasion but are
never capable of realization, serve to point out to us actually not only the bounds of the
pure use of reason, but also the way to determine them. Such is the end and the use of
this natural predisposition of our reason, which has brought forth metaphysics as its
favorite child, whose generation, like every other in the world, is not to be ascribed to
blind chance but to an original germ, wisely organized for great ends. For metaphysics,
in its fundamental features, perhaps more than any other science, is placed in us by
nature itself and cannot be considered the production of an arbitrary choice or a casual
enlargement in the progress of experience from which it is quite disparate.
Reason through all its concepts and laws of the understanding which are suffi-
cient to it for empirical use, that is, within the sensible world, finds in it no satisfac-
tion, because ever-recurring questions deprive us of all hope of their complete
solution. The transcendental Ideas which have that completion in view are such
problems of reason. But it sees clearly that the sensuous world cannot contain this
completion; neither, consequently, can all the concepts which serve merely for
understanding the world of sense, for example, space and time, and what we have
adduced under the name of pure concepts of the understanding. The sensuous world
is nothing but a chain of appearances connected according to universal laws; it has
therefore no subsistence by itself; it is not the thing in itself, and consequently must
point to that which contains the basis of this appearance, to beings which cannot be
known merely as appearances, but as things in themselves. In the knowledge of them
alone can reason hope to satisfy its desire for completeness in proceeding from the
conditioned to its conditions.
We have above (§§ 33 and 34) indicated the limits of reason with regard to all
knowledge of mere beings of thought. Now, since the transcendental Ideas have made it
necessary to approach them and thus have led us, as it were, to the spot where the occu-
pied space (namely, experience) touches the void (that of which we can know nothing,
namely,noumena), we can determine the bounds of pure reason. For in all bounds there is
something positive (for example, a surface is the boundary of corporeal space, and is
therefore itself a space; a line is a space, which is the boundary of the surface, a point the
boundary of the line, but yet always a place in space), but limits contain mere negations.
The limits pointed out in those paragraphs are not enough after we have discovered that
beyond them there still lies something (though we can never know what it is in itself). For
the question now is, What is the attitude of our reason in this connection of what we know
with what we do not, and never shall, know? This is an actual connection of a known thing
with one quite unknown (and which will always remain so), and though what is unknown
should not become in the least more known—which we cannot even hope—yet the con-
cept of this connection must be definite and capable of being rendered distinct.354