objects; or of objects again as formed by abstraction into a collective
notion of matter, and of matter as rarefied into space. And motion may be
conceived as the union of there and not there in space, and force as the
materializing or solidification of motion. Space again is the individual
and universal in one; or, in other words, a perception and also a
conception. So easily do what are sometimes called our simple ideas pass
into one another, and differences of kind resolve themselves into
differences of degree.

Within or behind space there is another abstraction in many respects
similar to it--time, the form of the inward, as space is the form of the
outward. As we cannot think of outward objects of sense or of outward
sensations without space, so neither can we think of a succession of
sensations without time. It is the vacancy of thoughts or sensations, as
space is the void of outward objects, and we can no more imagine the mind
without the one than the world without the other. It is to arithmetic what
space is to geometry; or, more strictly, arithmetic may be said to be
equally applicable to both. It is defined in our minds, partly by the
analogy of space and partly by the recollection of events which have
happened to us, or the consciousness of feelings which we are experiencing.
Like space, it is without limit, for whatever beginning or end of time we
fix, there is a beginning and end before them, and so on without end. We
speak of a past, present, and future, and again the analogy of space
assists us in conceiving of them as coexistent. When the limit of time is
removed there arises in our minds the idea of eternity, which at first,
like time itself, is only negative, but gradually, when connected with the
world and the divine nature, like the other negative infinity of space,
becomes positive. Whether time is prior to the mind and to experience, or
coeval with them, is (like the parallel question about space) unmeaning.
Like space it has been realized gradually: in the Homeric poems, or even