tue of this process there is said to be 'unity of
consciousness in the synthesis of the manifold', a phrase which the
context justifies us in understanding as a condensed expression for a
situation in which (1) the manifold of sense is a unity of necessarily
related parts, (2) there is _consciousness_ of this unity, and (3) the
consciousness which combines and is conscious of combining the
manifold, as being necessarily one and the same throughout this
process, is itself a unity.

Kant then proceeds to introduce what he evidently considers the
keystone of his system, viz. 'transcendental apperception.'

"There is always a transcendental condition at the basis of any
necessity. Hence we must be able to find a transcendental ground of
the unity of consciousness in the synthesis of the manifold of all our
perceptions, and therefore also of the conceptions of objects in
general, consequently also of all objects of experience, a ground
without which it would be impossible to think any object for our
perceptions; for this object is no more than that something, the
conception of which expresses such a necessity of synthesis."

"Now this original and transcendental condition is no other than
_transcendental apperception_. The consciousness of self according to
the determinations of our state in internal sense-perception is merely
empirical, always changeable; there can be no fixed or permanent self
in this stream of internal phenomena, and this consciousness is
usually called _internal sense_ or _empirical apperception_. That
which is _necessarily_ to be represented as numerically identical
cannot be thought as such by means of empirical data. The condition
which is to make such a transcendental presupposition valid must be
one which precedes all experience, and makes experience itself
possible."

"Now no cognitions[52] can occur in us, no combination and unity of
them with one another, without that unity of consciousness which
precedes all data of perception, and by relation to which alone all
representation of objects is possible. This pure original unchangeable
consciousness I shall call _transcendental apperception_. That it
deserves this name is clear from the fact that even the purest
objective unity, viz. that of _a priori_ conceptions (space and time)
is only possible by relation of perceptions to it. The numerical unity
of this apperception therefore forms the _a priori_ foundation of all
conceptions, just as the