In this way each time-system possesses its own permanent timeless space peculiar to it alone, and each such space is composed of timeless points which belong to that time-system and to no other.

The paradoxes of relativity arise from neglecting the fact that different assumptions as to rest involve the expression of the facts of physical science in terms of radically different spaces and times, in which points and moments have different meanings.
The source of order has already been indicated and that of congruence is now found.

It depends on motion.

From cogredience, perpendicularity arises; and from perpendicularity in conjunction with the reciprocal symmetry between the relations of any two time-systems congruence both in time and space is completely defined (cf._loc.

cit._).
The resulting formulae are those for the electromagnetic theory of relativity, or, as it is now termed, the restricted theory.