“Like every other destruction of optimism, whether in a whole civilisation or in a single individual, these must have been unspeakable catastrophes for those who had dared to expect progress. But we should feel more than sympathy for those people. We should take it personally. For if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal.”

“The whole [scientific] process resembles biological evolution. A problem is like an ecological niche, and a theory is like a gene or a species which is being tested for viability in that niche.”

“we had more people begging for snow than those that had bet on a white Christmas”

“Feeling insignificant because the universe is large has exactly the same logic as feeling inadequate for not being a cow.”

“Custom, then, is the great guide of human life. It is that principle alone which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past. Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses. We should never know how to adjust means to ends, or to employ our natural powers in the production of any effect. There would be an end at once of all action, as well as of the chief part of speculation.”

“My mother once told me, when you have to make a decision, imagine the person you want to become someday. Ask yourself, what would that person do?”

“The test of our progress is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little.”