If your theory is found to be against the second law of thermodynamics I give you no hope; there is nothing for it but to collapse in deepest humiliation.

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.

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

It is impossible to trap modern physics into predicting anything with perfect determinism because it deals with probabilities from the outset.

Man is slightly nearer to the atom than to the star. ... From his central position man can survey the grandest works of Nature with the astronomer, or the minutest works with the physicist. ... [K]nowledge of the stars leads through the atom; and important knowledge of the atom has been reached through the stars.

It is also a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.

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.'