Even the development of the steam engine owed but little to the advancement of science.

Whether a man lives or dies in vain can be measured only by the way he faces his own problems, by the success or failure of the inner conflict within his own soul. And of this no one may know save God.

I venture to define science as a series of interconnected concepts and conceptual schemes arising from experiment and observation and fruitful of further experiments and observations. The test of a scientific theory is, I suggest, its fruitfulness.

A conceptual scheme is never discarded merely because of a few stubborn facts with which it cannot be reconciled; a conceptual scheme is either modified or replaced by a better one, never abandoned with nothing left to take its place.

The stumbling way in which even the ablest of the scientists in every generation have had to fight through thickets of erroneous observations, misleading generalizations, inadequate formulation, and unconscious prejudice is rarely appreciated by those who obtain their scientific knowledge from textbooks.

Public education is a great instrument of social change. Through it, if we so desire, we can make our country more nearly a democracy without classes. To do so will require the efforts of us all-teachers, administrators, taxpayers and statesmen. Education is a social process, perhaps the most important process in determining the future of our country; it should command a far larger portion of our national income than it does today.

Each honest calling, each walk of life, has its own elite, its own aristocracy based on excellence of performance. . . . There will always be the false snobbery which tries to place one vocation above another. You will become a member of the aristocracy in the American sense only if your accomplishments and integrity earn this appellation.