In the case of composite colour, an infinity of systems must be obtained for maxima infinitely slight and with an infinity of interval values separating them - that is to say, the whole thickness of the sensitive layer is occupied in continuous manner by these maxima.
Gabriel Lippmann[On the Gaussian curve, remarked to Poincarรฉ:] Experimentalists think that it is a mathematical theorem while the mathematicians believe it to be an experimental fact.
Gabriel Lippmann