“We’re living in topsy-turvy times, and I think that what causes the topsy-turvy feeling is inadequacy of old forms of thought to deal with new experiences. I’ve heard it said that the only real learning results from hang-ups, where instead of expanding the branches of what you already know, you have to stop and drift laterally for a while until you come across something that allows you to expand the roots of what you already know. Everyone’s familiar with that. I think the same thing occurs with whole civilizations when expansion’s needed at the roots.”