A theory of motion and a theory of rest are the same thing viewed from different aspects with altered emphasis.
Now you cannot have a theory of rest without in some sense admitting a theory of absolute position.

It is usually assumed that relative space implies that there is no absolute position.

This is, according to my creed, a mistake.

The assumption arises from the failure to make another distinction; namely, that there may be alternative definitions of absolute position.

This possibility enters with the admission of alternative time-systems.