Cock-sure certainty is the source of much that is worst in our present world, and it is something of which the contemplation of history ought to cure us, not only or chiefly because there were wise men in the past, but because so much that was thought wisdom turned out to be folly – which suggests that much of our own supposed wisdom is no better. I do not mean to maintain that we should lapse into a lazy scepticism. We should hold our beliefs, and hold them strongly. Nothing great is achieved without passion, but underneath the passion there should always be that large impersonal survey which sets limits to actions that our passions inspire.