It is reasonable to hope that in the not too distant future we shall be competent to understand so simple a thing as a star.

Schrödinger's wave-mechanics is not a physical theory, but a dodge - and a very good dodge too.

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

Science is one thing, wisdom is another. Science is an edged tool, with which men play like children, and cut their own fingers. If you look at the results which science has brought in its train, you will find them to consist almost wholly in elements of mischief. See how much belongs to the word "Explosion" alone, of which the ancients knew nothing.

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.

It is a primitive form of thought that things exist or do not exist.

Who will observe the observers?