(a) Time is not something which subsists of itself, or which inheres in
things as an objective determination, and therefore remains, when
abstraction is made of the subjective conditions of the intuition of
things. For in the former case, it would be something real, yet without
presenting to any power of perception any real object. In the latter
case, as an order or determination inherent in things themselves, it
could not be antecedent to things, as their condition, nor discerned or
intuited by means of synthetical propositions à priori. But all this is
quite possible when we regard time as merely the subjective condition
under which all our intuitions take place. For in that case, this form
of the inward intuition can be represented prior to the objects, and
consequently à priori.
(b) Time is nothing else than the form of the internal sense, that is,
of the intuitions of self and of our internal state. For time cannot be
any determination of outward phenomena. It has to do neither with shape
nor position; on the contrary, it determines the relation of
representations in our internal state. And precisely because this
internal intuition presents to us no shape or form, we endeavour to
supply this want by analogies, and represent the course of time by a
line progressing to infinity, the content of which constitutes a series
which is only of one dimension; and we conclude from the properties of
this line as to all the properties of time, with this single exception,
that the parts of the line are coexistent, whilst those of time are
successive. From this it is clear also that the representation of time
is itself an intuition, because all its relations can be expressed in
an external intuition.
(c) Time is the formal condition à priori of all phenomena whatsoever.
Space, as the pure form of external intuition, is limited as a
condition à priori to external phenomena alone. On the other hand,
because all representations, whether they have or have not external
things for their objects, still in themselves, as determinations of the
mind, belong to our internal state; and because this internal state is
subject to the formal condition of the internal intuition, that is, to
time—time is a condition à priori of all phenomena whatsoever—the
immediate condition of all internal, and thereby the mediate condition
of all external phenomena. If I can say à priori, “All outward
phenomena are in space, and determined à priori according to the
relations of space,” I can also, from the principle of the internal
sense, affirm universally, “All phenomena in general, that is, all
objects of the senses, are in time and stand necessarily in relations
of time.”