"Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to repeat it."

“Eternal vigilance is the price of knowledge.”

“American life is a powerful solvent. As it stamps the immigrant, almost before he can speak English, with an unmistakable muscular tension, cheery self-confidence and habitual challenge in the voice and eyes, so it seems to neutralize every intellectual element, however tough and alien it may be, and to fuse it in the native good-will, complacency, thoughtlessness, and optimism.”

“The soul, too, has her virginity and must bleed a little before bearing fruit.”

“It is not society's fault that most men seem to miss their vocation. Most men have no vocation.”

“Skepticism, like chastity, should not be relinquished too readily.”

“Perhaps the only true dignity of man is his capacity to despise himself.”