A man far oftener appears to have a decided character from persistently following his temperament than from persistently following his principles. Human, All Too Human

If the Easter Islanders couldn't solve their milder local problems in the past, how can the modern world hope to solve its big global problems? People who get depressed at such thoughts often then ask me, “Jared, are you optimistic or pessimistic about the world’s future?” I answer, “I am a cautious optimist.” By that, I mean that, on the one hand, I acknowledge the seriousness of the problems facing us. If we don’t make a determined effort to solve them, and if we don’t succeed at that effort, the world as a whole within the next few decades will face a declining standard of living, or perhaps something worse. That’s the reason why I decided to devote most of my career efforts at this stage of my life to convincing people that our problems have to be taken seriously and won’t go away otherwise. On the other hand, we shall be able to solve our problems – if we choose to do so. Collapse: How Societies Choose to Fail or Succeed

What good is the warmth of summer, without the cold of winter to give it sweetness. Travels with Charley: In Search of America

That which comes after ever conforms to that which has gone before. Book IV