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

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

In the world of physics we watch a shadowgraph performance of the drama of familiar life. The shadow of my elbow rests on the shadow table as the shadow ink flows over the shadow paper. It is all symbolic, and as a symbol the physicist leaves it. ... The frank realisation that physical science is concerned with a world of shadows is one of the most significant of recent advances.

We often think that when we have completed our study of one we know all about two, because 'two' is 'one and one.' We forget that we still have to make a study of 'and.'

Oh leave the Wise our measures to collate. One thing at least is certain, light has weight. One thing is certain and the rest debate. Light rays, when near the Sun, do not go straight.

An electron is no more (and no less) hypothetical than a star. Nowadays we count electrons one by one in a Geiger counter, as we count the stars one by one on a photographic plate.

We have found that where science has progressed the farthest, the mind has but regained from nature that which the mind put into nature.