Like most animals, we don't much like really hot places, but because we sweat so freely and easily stroke, we are especially vulnerable. 像大多数动物一样，我们不大喜欢太热的地方——我们挥汗如雨，很容易中暑，特别吃不起苦。

　　In the worst circumstances—on foot without water in a hot desert, 在最恶劣的条件下——在没有水的情况下在沙漠里走路，

　　most people will grow delirious and keel over, possibly never to rise again, in no more than six or seven hours. 大多数人会神志昏乱，晕倒在地，很可能再也起不来，总共不消七八个小时。

　　We are no less helpless in the face of cold.  面对寒冷我们也同样束手无策。

　　Like all mammals, humans are good at generating heat but—because we are so nearly hairless—not good at keeping it. 像所有哺乳动物一样，人类产生热量的本事不小；但是——由于我们身上几乎没有毛——我们保存热量的本事不大。

　　Even in quite mild weather half the calories you burn go to keep your body warm. 即使在相当暖和的天气里，也有一半卡路里是用于保暖身体的。

　　Of course, we can counter these frailties to a large extent by employing clothing and shelter, 当然，在很大程度上，我们可以利用衣服和房屋来弥补这些不足，

　　but even so the portions of Earth on which we are prepared or able to live are modest indeed: 即使那样，地球上我们愿意或能够生存的部分也相当有限：

　　just 12 percent of the total land area, and only 4 percent of the whole surface if you include the seas. 只占陆地总面积的12%；要是包括海洋在内的话，只占地球表面总面积的4%。

　　Yet when you consider conditions elsewhere in the known universe, 然而，要是你把已知宇宙的其他地方的条件考虑进去，

　　the wonder is not that we use so little of our planet but that we have managed to find a planet that we can use even a bit of. 令人惊奇的不是我们使用了我们行星的那么一丁点儿地方，而是我们竟然还找到了一个能使用那么一丁点儿地方的行星。

　　You have only to look at our own solar system—or, come to that, Earth at certain periods in its own history, 你只要看一眼我们自己的太阳系——或者只要看一眼某些历史时期的地球，

　　to appreciate that most places are much harsher and much less amenable to life than our mild, blue watery globe. 就会知道，大多数地方对待生命比我们这暖融融、蓝盈盈、水灵灵的地球要无情得多，粗暴的多。