Fear is the main source of superstition, and one of the main sources of cruelty. To conquer fear is the beginning of wisdom.
A life without adventure is likely to be unsatisfying, but a life in which adventure is allowed to take whatever form it will is sure to be short.
A process which led from the amoebae to man appeared to the philosophers to be obviously a progress – though whether the amoebae would agree with this opinion is not known.
Against my will, in the course of my travels, the belief that everything worth knowing was known at Cambridge gradually wore off. In this respect my travels were very useful to me.
A sense of duty is useful in work but offensive in personal relations. People wish to be liked, not to be endured with patient resignation.
