"War, as I remarked a moment ago, has hitherto been disappointing in this respect, but perhaps bacteriological war may prove more effective. If a Black Death could be spread throughout the world once i…"

"To teach how to live without certainty, and yet without being paralysed by hesitation, is perhaps the chief thing that philosophy, in our age, can still do for those who study it."

"The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt."

"The trouble with the world is that the intelligent people are full of doubts, while the stupid ones are full of confidence."

"A good social system is not to be secured by making people unselfish, but, by making their own vital impulses fit in with other peoples."