he universal. To
say that we can only have a true idea of ourselves when we deny the
reality of that by which we have any idea of ourselves is an absurdity.
The earth which is our habitation and 'the starry heaven above' and
we ourselves are equally an illusion, if space is only a quality or
condition of our minds.

Again, we may compare the truths of space with other truths derived from
experience, which seem to have a necessity to us in proportion to the
frequency of their recurrence or the truth of the consequences which may
be inferred from them. We are thus led to remark that the necessity
in our ideas of space on which much stress has been laid, differs in a
slight degree only from the necessity which appears to belong to other
of our ideas, e.g. weight, motion, and the like. And there is another
way in which this necessity may be explained. We have been taught it,
and the truth which we were taught or which we inherited has never been
contradicted in all our experience and is therefore confirmed by it. Who
can resist an idea which is presented to him in a general form in every
moment of his life and of which he finds no instance to the contrary?
The greater part of what is sometimes regarded as the a priori intuition
of space is really the conception of the various geometrical figures of
which the properties have been revealed by mathematical analysis. And
the certainty of these properties is immeasurably increased to us by our
finding that they hold good not only in every instance, but in all the
consequences which are supposed to flow from them.

Neither must we forget that our idea of space, like our other ideas,
has a history. The Homeric poems contain no word for it; even the later
Greek philosophy has not the Kantian notion of space, but only the
definite 'place' or 'the infinite.' To Plato, in the Timaeus, it is
known only as the 'nurse of generation.' When therefore we speak of
the necessity of our ideas of space we must remember that this is a
necessity which has grown up with the growth of the human mind, and
has been made by ourselves. We can free ourselves from the perplexities
which are involved in it by ascending to a time in which they did not
as yet exist. And when space or time are described as 'a priori forms or
intuitions added to the matter given in sensation,' we should consider
that such expressions belong really to the 'pre-historic study' of
philosophy, i.e. to the eighteenth century, whe