I can see no more reason for preferring the theories of fifty years ago than for preferring the observational data of fifty years ago. - Arthur Eddington

To the pure geometer the radius of curvature is an incidental characteristic — like the grin of the Cheshire cat. To the physicist it is an indispensable characteristic. It would be going too far to say that to the physicist the cat is merely incidental to the grin. Physics is concerned with interrelatedness such as the interrelatedness of cats and grins. In this case the "cat without a grin" and the "grin without a cat" are equally set aside as purely mathematical phantasies.

Consciousness is not wholly, nor even primarily a device for receiving sense-impressions. … there is another outlook than the scientific one, because in practice a more transcendental outlook is almost universally admitted. … who does not prize these moments that reveal to us the poetry of existence?

By his theory of relativity Albert Einstein has provoked a revolution of thought in physical science. ...Physical space and time are found to be closely bound... with... motion of the observer; and only an amorphous combination of the two is left... It is my aim to give an account of this work without introducing anything very technical in... mathematics, physics, or philosophy. ...[T]he task is one of interpreting a clear-cut theory... although perhaps not everyone would accept the author's views of its meaning.