Protoplasm, simple or nucleated, is the formal basis of all life. It is the clay of the potter: which, bake it and paint it as hewill, remains clay, separated by artifice, and not by nature from the commonest brick or sun-dried clod.

The great end of life is not knowledge but action.

Try to learn something about everything and everything about something.

The world is neither wise nor just, but it makes up for all its folly and injustice by being damnably sentimental.

Science seems to me to teach in the highest and strongest manner the great truth which is embodied in the Christian conception of entire surrender to the will of God. Sit down before fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever and to whatever abysses nature leads, or you shall learn nothing. I have only begun to learn content and peace of mind since I have resolved at all risks to do this.

The supernatural is being swept out of the universe in the flood of new knowledge of what is natural. It will soon be as impossible for an intelligent, educated man or woman to believe in a god as it is now to believe that earth is flat, that flies can be spontaneously generated, that disease is a divine punishment, or that death is always due to witchcraft.

A well-worn adage advises those who set out upon a great enterprise to count the cost, yet some of the greatest enterprises have succeeded because the people who undertook them did not count the cost.