them and whatever is involved in A. The mind's own rule holds good in
all cases, because the mind has itself determined the nature of the
cases.

Kant's statements about physics, though not the same, are analogous.
Experiment, he holds, is only fruitful when reason does not follow
nature in a passive spirit, but compels nature to answer its own
questions. Thus, when Torricelli made an experiment to ascertain
whether a certain column of air would sustain a given weight, he had
previously calculated that the quantity of air was just sufficient to
balance the weight, and the significance of the experiment lay in his
expectation that nature would conform to his calculations and in the
vindication of this expectation. Reason, Kant says, must approach
nature not as a pupil but as a judge, and this attitude forms the
condition of progress in physics.

The examples of mathematics and physics suggest, according to Kant,
that metaphysics may require a similar revolution of standpoint, the
lack of which will account for its past failure. An attempt should
therefore be made to introduce such a change into metaphysics. The
change is this. Hitherto it has been assumed that our knowledge must
conform to objects. This assumption is the real cause of the failure
to extend our knowledge _a priori_, for it limits thought to the
analysis of conceptions, which can only yield tautological judgements.
Let us therefore try the effect of assuming that objects must conform
to our knowledge. Herein lies the Copernican revolution. We find that
this reversal of the ordinary view of the relation of objects to the
mind enables us for the first time to understand the possibility of _a
priori_ synthetic judgements, and even to demonstrate certain laws
which lie at the basis of nature, e. g. the law of causality. It is
true that the reversal also involves the surprising consequence that
our faculty of knowledge is incapable of dealing with the objects of
metaphysics proper, viz. God, freedom, and immortality, for the
assumption limits our knowledge to objects of possible experience. But
this very consequence, viz. the impossibility of metaphysics, serves
to test and vindicate the assumption. For the view that our knowledge
conforms to objects as things in themselves leads us into an insoluble
contradiction when we go on, as we must, to seek for the
unconditioned; while the assumption that objects must, as phenomena,
conform to our way of representin