Verily, it is easier for a camel to pass through the eye of a needle than for a scientific man to pass through a door. And whether the door be barn door or church door it might be wiser that he should consent to be an ordinary man and walk in rather that wait till all the difficulties involved in a really scientific ingress are resolved.
The Nature of the Physical World, Chapter XV (p. 342), The Macmillan Company. 1930