On Theories (Unsourced)

"First a new theory is attacked as absurd; then it is admitted to be true, but obvious and insignificant; finally it is seen to be so important that its adversaries claim they themselves discovered it.” (William James)

“Such is the advantage of a well-constructed language that its simplified notation often becomes the source of profound theories.” (Pierre-Simon Laplace)

"Somewhere out there is a theory that would explain my empirical observations, and this theory has yet to be discovered. Mathematics thrives on such mysteries.” (Henri Darmon)

“A theory is a supposition which we hope to be true, a hypothesis is a supposition which we expect to be useful; fictions belong to the realm of art; if made to intrude elsewhere, they become either make-believes or mistakes.” (G Johnstone Stoney)

"There is nothing more practical than a good theory.” ([attributed to] David Hilbert)

“Theory helps us to bear our ignorance of facts.” (George Santayana)

“What is especially striking and remarkable is that in fundamental physics, a beautiful or elegant theory is more likely to be right than a theory that is inelegant. A theory appears to be beautiful or elegant (or simple, if you prefer) when it can be expressed concisely in terms of mathematics we already have.” (Murray Gell-Mann)

"A mark of a good theory is that it proves even the most trivial results." (Hector Sussmann)

”If the facts do not conform to the theory, they must be disposed of.” (Norman R F Maier)

“First accumulate a mass of Facts: and then construct a Theory.” (Lewis Carroll)