"If you have observed nature, you would have proved that the question of the numbers of mates is certainly not a question of arithmetic. With gnats, ten females are born to one male. Now gnats are not polygamous. Nine out of those females dies spinsters. It is only the old maids who bite us, from which one sees that celibacy engenders ferocity among insects as well as among women."

“Our poor bodies have strength and resources that we learn to know only when we are in the gravest situations.”

“The art of resting is a part of the art of working. A man who is tired and greatly in need of rest cannot do any good work. We are all familiar with those terrible mornings after sleepless nights when our brains refuse to function. It would be useless then to attempt to apply the principles of the art of working. Those principles presuppose mind and body to be in good condition. The human organism cannot live without alternating work and rest.”

“Almost all of our fellow-beings deceive us, but a few of us have known the joy of meeting a woman or a man whose sincerity and frankness were genuine, who in almost every situation has behaved according to our wishes, and who in our most difficult moments has not forsaken us. Those few are familiar with that marvelous feeling: confidence. With at least one person they are able for a little while each day to lift the heavy visor of their helmets, breathe freely, and show their faces and their hearts without fear.”

“To amuse is not to teach. The object of teaching is to erect a framework of knowledge in a child's mind and gradually to bring the child as near as may be to the average level of intelligence. Later in life the facts taught by experience and new discoveries will add themselves to this framework. It is wrong to attempt to upset this natural order and to appeal to a child's mind by diverting it with the spectacle of modern life. Teaching by means of pictures, radio, and the cinema is in itself ineffective; these methods must not be used unless they involve some effort or special enthusiasm. That which is learned without difficulty is soon forgotten, and for the same reason, oral instruction which does not require the pupil's personal participation is almost always rather useless. Eloquence slides in and out of young minds. To listen is not to work.”

“Marriage makes a man more vulnerable by doubling the expanse of sail exposed to the tempests of social life.”

“The aspiring author, whether genius or not, should never let a day pass without writing at least a few lines.”