Nature is man's teacher. She unfolds her treasures to his search, unseals his eye, illumes his mind, and purifies his heart; an influence breathes from all the sights and sounds of her existence.

A heart can no more be forced to love than a stomach can be forced to digest food by persuasion.

One can state, without exaggeration, that the observation of and the search for similarities and differences are the basis of all human knowledge.

It is my express wish that in awarding the [Nobel Prizes] no consideration be given to the nationality of the candidates, but that the most worthy shall receive the prize, whether he be Scandinavian or not.

Contentment is the only real wealth.

Worry is the stomach's worst poison.

To his sister-in-law: What a contrast between us! You live a warm and glowing life, surrounded by loved ones whom you care for and who care for you; you are anchored in contentment. I drift about without rudder or compass, a wreck on the sea of life; I have no memories to cheer me, no pleasant illusions of the future to comfort me, or about me to satisfy my vanity. I have no family to furnish the only kind of survival that concerns us, no friends for the wholesome development of my affections, or enemies for my malice.