...Newton's monochromator turned out to be not perfect enough, despite him using a collimator with a narrow slit; fluorescence in homogeneous lighting Newton did not notice, and the principle was saved. We see here a not-so-rare case of the imperfection of experiment facilitating the development of science. It is hard to imagine the confusion in optical ideas if Stokes's shift had been discovered in the XVIIth century.

• S. I. Vavilov, The principles and hypotheses of Newton's optics (a kind of introduction to two Newton's optical memoirs he translated into Russian), 1927.