If you can not measure it, you can not improve it.

If we can't express what we know in the form of numbers, we really don't know much about it.

We all confidently believe that there are at present, and have been from time immemorial, many worlds of life besides our own. . . . [This] may seem wild, and visionary; all I maintain is that it is not unscientific.

Fourier's theorem is not only one of the most beautiful results of modern analysis, but it may be said to furnish an indispensable instrument in the treatment of nearly every recondite question in modern physics.

Large increases in cost with questionable increases in performance can be tolerated only in race horses and fancy women.

Questions of personal priority, however interesting they may be to the persons concerned, sink into insignificance in the prospect of any gain of deeper insight into the secrets of nature.

I need scarcely say that the beginning and maintenance of life on earth is absolutely and infinitely beyond the range of all sound speculation in dynamical science. The only contribution of dynamics to theoretical biology is absolute negation of automatic commencement or automatic maintenance of life.