“I consider the official Catholic attitude on divorce, birth control, and censorship exceedingly dangerous to mankind.”

“The only thing that will redeem mankind is cooperation.”

“Moreover, the attitude that one ought to believe such and such a proposition, independently of the question whether there is evidence in its favor, is an attitude which produces hostility to evidence and causes us to close our minds to every fact that does not suit our prejudices.”

“Official morality has always been oppressive and negative: it has said "thou shalt not," and has not troubled to investigate the effect of activities not forbidden by the code.”

“It is possible that mankind is on the threshold of a golden age; but, if so,it will be necessary first to slay the dragon that gaurds the door,and this dragon is religion”

“a generation that cannot endure boredom will be a generation of little men, of men unduly divorced from the slow process of nature, of men in whom every vital impulse slowly withers as though they were cut flowers in a vase.”

“Three passions, simple but overwhelmingly strong have governed my life: the longing for love, the search for knowledge, and unbearable pity for the suffering of mankind.”