The understanding between a non-technical writer and his reader is that he shall talk more or less like a human being and not like an Act of Parliament. I take it that the aim of such books must be to convey exact thought in inexact language... he can never succeed without the co-operation of the reader.

For the truth of the conclusions of physical science, observation is the supreme Court of Appeal.

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.

We are bits of stellar matter that got cold by accident, bits of a star gone wrong.

There is no space without aether, and no aether which does not occupy space.

Something unknown is doing we don't know what-that is what our theory amounts to.

Proof is an idol before which the mathematician tortures himself.