sisting, as Kant held, of certain crude data supplied by
sensation, colours, tones of varying pitch and loudness, odours,
savours, and the like. It has also a _form_ or formal constituent. Our
data, when we know anything at all, are arranged on some definite
principle of order. When we recognize an object by the eye or a tune by
the ear, we do not apprehend simply so much colour or sound, but colours
spread out and forming a pattern or notes following one another in a
fixed order. (If you reverse the movement of a gramophone, you get the
same notes as before, but you do not get the same tune.) Further, Kant
thought it could be shown that the data of our knowledge are a
disorderly medley and come to us from without, being supplied by things
which exist and are what they are equally whether any one perceives them
or not, but the element of form, pattern, or order is put into them by
our own minds in the act of knowing them. Our minds are so constructed
that we _can_ only perceive things or think of them as connected by
certain definite principles of orderly arrangement. This, he thought,
explains the indubitable fact that we can sometimes know universal
propositions to be true without needing to examine all the individual
instances. I can know for certain that in every triangle the greater
angle is subtended by the greater side, or that every event has a
definite cause among earlier events, though I cannot examine all
triangles or all events one by one. This is because the postulates of
geometry and the law of causality are types of order which my mind
_puts_ into the data of its knowledge in the very act of attending to
them, and it is therefore certain that I shall never perceive or think
anything which does not conform to these types.

I give Kant's answer to the problem of Criticism not because I believe
it to be the correct one, but to show what important consequences follow
from our acceptance of a solution of this problem. If it is true that
one of the constituent elements of every piece of knowledge is a lump of
crude sensation, it follows that we can have no knowledge about our own
minds or souls, and still less about God, since, if there are such
beings as my soul and God, at any rate neither furnishes me with
sense-data. Hence a great part of Kant's famous _Critique of Pure
Reason_ is taken up by an elaborate attempt to show that psychology and
theology contain no real knowledge. We cannot even know whether ther