On the left-hand side of the field equation we may add the fundamental tensor guv, multiplied by a universal constant, -λ, at present unknown, without destroying the general covariance.
I soon learned how to scent out that which was able to lead to fundamentals and to turn aside everything else, from the multitude of things that clutter up the mind and divert it from the essential.
If one asks the whence derives the authority of fundamental ends, since they cannot be stated and justified merely by reason, one can only answer: they exist in a healthy society as powerful traditions, which act upon the conduct and aspirations and judgments of the individuals; they are there, that is, as something living, without its being necessary to find justification for their existence.