wise? Why, for instance, do I always see people's eyes above their mouths and not below them?
According to Kant, the eyes and the mouth exist as things in themselves, and cause my separate
percepts, but nothing in them corresponds to the spatial arrangement that exists in my perception.
Contrast with this the physical theory of colours. We do not suppose that in matter there are
colours in the sense in which our percepts have colours, but we do think that different colours
correspond to different wave-lengths. Since waves, however, involve space and time, there
cannot, for Kant, be waves in the causes of our percepts. If, on the other hand, the space and time
of our percepts have counterparts in the world of matter, as physics assumes, then geometry is
applicable to these counterparts, and Kant's arguments fail. Kant holds that the mind orders the
raw material of sensation, but never thinks it necessary to say why it orders it as it does and not
otherwise.
In regard to time this difficulty is even greater, because of the intrusion of causality. I perceive the
lightning before I perceive the thunder; a thing-in-itself A caused my perception of lightning, and
another thing-in-itself B caused my perception of thunder, but A was not earlier than B, since time
exists only in the relations of percepts. Why, then, do the two timeless things A and B produce
effects at different times? This must be wholly arbitrary if Kant is right, and there must be no
relation betwen A and B corresponding to the fact that the percept caused by A is earlier than that
caused by B.
The second metaphysical argument maintains that it is possible to imagine nothing in space, but
impossible to imagine no space. It seems to me that no serious argument can be based upon what
we can or cannot imagine; but I should emphatically deny that we can imagine space with nothing
in it. You can imagine looking at the sky on a dark cloudy night, but then you yourself are in
space, and you imagine the clouds that you cannot see. Kant's space is absolute, like Newton's,
and not merely a system of relations. But I do not see how absolute empty space can be imagined.
The third metaphysical argument says: "Space is not a discursive, or, as is said, general concept of
the relations of things in general, but a pure intuition. For, in the first place, we can only imagine
[sich vorstellen] one single space, and if we speak of 'spaces' we mean only parts of one and the
same unique space. And these parts cannot precede the whole as its parts... but can only be
thought as in it. It