I do not propose to argue the case for evolution, which I regard as being quite as well proven as most other historical facts, but to discuss its pos… - J.B.S. Haldane

In scientific thought we adopt the simplest theory which will explain all the facts under consideration and enable us to predict new facts of the same kind. The catch in this criterion lies in the word "simplest." It is really an aesthetic canon such as we find implicit in our criticisms of poetry or painting. The layman finds such a law as <math> {\mathrm{\partial }x \over \mathrm{\partial } t} = \Kappa { \, \mathrm{\partial}^2x \over \mathrm{\partial }y^2}</math> much less simple than "it oozes," of which it is the mathematical statement. The physicist reverses this judgment, and his statement is certainly the more fruitful of the two, so far as prediction is concerned. It is, however, a statement about something very unfamiliar to the plain man, namely, the rate of change of a rate of change.

The conservative has but little to fear from the man whose reason is the servant of his passions, but let him beware of him in whom reason has become the greatest and most terrible of the passions. These are the wreckers of outworn empires and civilisations, doubters, disintegrators, deicides.

The Universe is not only queerer than we suppose, but queerer than we can suppose.