Here's a rule thumb that's important, and the older I get, the more important I think it is. When I can do something, and somebody wants me to do it, I have to do it. The great tragedy of life is not to be needed. As long as you are able and willing to do things for people, you will be needed. Of course you are able; and if so, you can't say no. My mother is seventy-seven. In seventy-seven years she has never said no. Today she is so much in demand by thirteen grandchildren and countless neighbors that her presence is eagerly contended for. When I want to see her I have to pretend emergency.

此外，还有一条经验法则同样重要。随着慢慢长大，我也越来越认识到它的重要性。当我有能力做一件事，有人也希望我做时，我就必须去做。不为人所需是人生中最大的悲剧。只要你有能力并愿意为人们做一些事，人们就会需要你。你肯定能够做到，那就不要推辞。我的母亲已经77岁了。但77年来她从未说过“不”字。如今，她的13个孙儿和无数的邻居依然很需要她，希望她能在身边。因此当我想见她时，不得不假装有紧急的事情。

Then there's the rule of curiosity. Your body would die if you stopped feeling hunger and thirst, and your mind will die if you lose your curiosity. This I learned from my father. My father was a naturalist. He could see the beetle under the bark, and draw it forth unharmed for us to squint at through the magnifying glass. He sampled the taste of thirty-three different caterpillars. Fired by his example, once, my sister ate an ant. In case you are wondering, caterpillars taste like the green leaves they eat, and ants taste of lemon. I personally haven't tasted any entomological specimens lately, but I am still rejoicing in the limitless curiosity, the draws me to books and people and places.I hope I never lose it. It would be like pulling down the blind.

除此之外，还有好奇法则。当你感觉不到饥饿和干渴时，你的身体就停止运转了；如果你失去了好奇心，那你的思想就不再工作了。这是父亲传授给我的。他是一位博物学家。他能看到树皮下的甲虫，并把它毫发无伤地捉下来，放在放大镜下让我们看。他尝过33种不同毛虫的味道。有一次，在父亲的示范与鼓励下，妹妹吃了一只蚂蚁。假如你对它们的味道感到好奇，我会告诉你，毛虫的味道就像它们所吃的树叶，而蚂蚁的味道像柠檬。我个人最近并未品尝任何昆虫的标本，但我仍欣喜于自己无限的好奇心，它促使我博览群书、乐于与人交往和四处旅行。我希望永远拥有好奇心。没有它，就仿佛放下了窗帘，让我无法欣赏到窗外的美景。