- For although it is certainly true that quantitative measurements are of great importance, it is a grave error to suppose that the whole of experimental physics can be brought under this heading. We can start measuring only when we know what to measure: qualitative observation has to precede quantitative measurement, and by making experimental arrangements for quantitative measurements we may even eliminate the possibility of new phenomena appearing.
- in his memoirs, as quoted by Jean Matricon, G. Waysand, Charles Glashausser (2003). The cold wars: a history of superconductivity. Rutgers University Press. p. 18. ISBN 0813532957.