In the study of physics, we see what are called individual facts but which are by no means isolated and which are not independent of each other; on the contrary they are related to each other by laws which the physicist devotes all his attention to discovering. It is this which is a measure of the true progress of the science.
In: Maurice Crosland, Gay-Lussac: Scientist and Bourgeois, Chapter 3 (p. 70), Cambridge University Press. 1978