At any given moment, men of science are close to the solutions of some
problems and remote from others. It must be remembered that necessity
is only the mother of invention; socially accumulated knowledge is its
father. Unless the two are brought together, necessity remains infertile.
She may of course conceive at some future time when she is properly mated.
But the mate requires time (and sustenance) if he is to attain the size
and vigor needed to meet the demands that will be made upon him (1968,