As truly as the mystic, the scientist is following a light; and it is not a false or an inferior light. - Arthur Eddington

We used to think that if we knew one, we knew two, because one and one are two. We are finding that we must learn a great deal more about ‘and.

It is perhaps difficult sufficiently to emphasise Seeking without disparaging its correlative Finding. But I must risk this, for Finding has a clamorous voice that proclaims its own importance; it is definite and assured, something that we can take hold of — that is what we all want, or think we want. Yet how transitory it proves.
The finding of one generation will not serve for the next. It tarnishes rapidly except it be reserved with an ever-renewed spirit of seeking.

The writings of Einstein, Minkowski, Hilbert, Lorentz, Weyl, Robb, and others, have provided the groundwork; in the give and take of debate with friends and correspondents, the extensive ramifications have gradually appeared.