“One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one’s greatest efforts.”

“Peace cannot be kept by force; it can only be achieved by understanding.”

“Only those who attempt the absurd can achieve the impossible.”

“The future is not a gift-it is an achievement.”

“The right to search for the truth implies also a duty; one must not conceal any part of what one has recognized to be the truth.”

“Those whose acquaintance with scientific research is derived chiefly from its practical results easily develop a completely false notion of the mentality of the men who, surrounded by a skeptical world, have shown the way to kindred spirits scattered wide through the world and through the centuries. Only one who has devoted his life to similar ends can have a vivid realization of what has inspired these men and given them the strength to remain true to their purpose in spite of countless failures. It is cosmic religious feeling that gives a man such strength. A contemporary has said, not unjustly, that in this materialistic age of ours the serious scientific workers are the only profoundly religious people.”

“There is far too great a disproportion between what one is and what others think one is, or at least what they say they think one is.”