The mathematician, carried along on his flood of symbols, dealing apparently with purely formal truths, may still reach results of endless importance for our description of the physical universe.

The right to live does not connote the right of each man to reproduce his kind ... As we lessen the stringency of natural selection, and more and more of the weaklings and the unfit survive, we must increase the standard, mental and physical, of parentage.

Medals are great encouragement to young men and lead them to feel their work is of value, I remember how keenly I felt this when in the 1890s. I received the Darwin Medal and the Huxley Medal. When one is old, one wants no encouragement and one goes on with one's work to the extent of one's power, because it has become habitual.

That which is measured improves. That which is measured and reported improves exponentially.

All great scientists have, in a certain sense, been great artists; the man with no imagination may collect facts, but he cannot make great discoveries.

When every fact, every present or past phenomenon of that universe, every phase of present or past life therein, has been examined, classified, and co-ordinated with the rest, then the mission of science will be completed. What is this but saying that the task of science can never end till man ceases to be, till history is no longer made, and development itself ceases?

The unity of all science consists alone in its method, not in its material.