Our model of Nature should not be like a building-a handsome structure for the populace to admire, until in the course of time some one takes away a corner stone and the edifice comes toppling down. It should be like an engine with movable parts. We need not fix the position of any one lever; that is to be adjusted from time to time as the latest observations indicate. The aim of the theorist is to know the train of wheels which the lever sets in motion-that binding of the parts which is the soul of the engine.

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.

Never accept a fact until it has been verified by theory.

In Einstein's theory of relativity the observer is a man who sets out in quest of truth armed with a measuring-rod. In quantum theory he sets out with a sieve.

Our ultimate analysis of space leads us not to a "here" and a "there," but to an extension such as that which relates "here" and "there." To put the conclusion rather crudely-space is not a lot of points close together; it is a lot of distances interlocked.

The word reality frightens me.

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