(for example) _Projective Geometry_ by Veblen and Young, vol.i.
1910, vol.ii.1917, Ginn and Company, Boston, U.S.A.
This theory lacks the two main supports of the corresponding theory of absolute time.

In the first place space does not extend beyond nature in the sense that time seems to do.

Our thoughts do not seem to occupy space in quite the same intimate way in which they occupy time.

For example, I have been thinking in a room, and to that extent my thoughts are in space.

But it seems nonsense to ask how much volume of the room they occupied, whether it was a cubic foot or a cubic inch; whereas the same thoughts occupy a determinate duration of time, say, from eleven to twelve on a certain date.
Thus whereas the relations of a relative theory of time are required to relate thoughts, it does not seem so obvious that the relations of a relative theory of space are required to relate them.