Any visitors to Earth from afar would almost certainly, at the very least, be bemused to find us living in an atmosphere composed of nitrogen, a gas sulkily disinclined to react with anything, and oxygen, which is so partial to combustion that we must place fire stations throughout our cities to protect ourselves from its livelier effects. But even if our visitors were oxygen-breathing bipeds with shopping malls and a fondness for action movies, it is unlikely that they would find Earth ideal. We couldn't even give them lunch because all our foods contain traces of manganese, selenium, zinc, and other elemental particles at least some of which would be poisonous to them. To them Earth might not seem a wondrously congenial place at all.
任何光临地球的远方客人几乎肯定都会觉得好笑，发现我们生活在一种由氮和氧组成的大气里。前者懒得不肯与任何东西发生化学反应；后者动不动就烧起来，我们不得不在城市的每个角落设置消防站，以免性情活泼的它对我们造成影响。即使我们的客人是呼吸氧气的两足动物，家乡设有大卖场，喜欢看情节片，他们也很可能觉得地球不是个很理想的环境。我们甚至无法招待他们吃午饭，因为我们的食物里都含有微量锰、硒、锌和别的元素粒子，起码其中有一些对他们来说是有毒性的。在他们看来，地球也许根本不是个很合意的地方。

The physicist Richard Feynman used to make a joke about a posteriori conclusions, as they are called. "You know, the most amazing thing happened to me tonight," he would say. "I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!" His point, of course, was that it is easy to make any banal situation seem extraordinary if you treat it as fateful.
物理学家里查得·费曼经常取笑事后下结论——从已知的事实往前推测可能的原因。“你要知道，今天晚上我遇到了一件最令人惊讶的事，”他会说，“我看到一辆汽车的牌照是ARW357。你想像得到吗？在我国几百万个牌照当中，今天晚上我怎么会偏偏看到那个牌照？真是不可思议！”当然，他的意思是，你很容易使任何平淡的事情显得很不寻常，如果你把它看得很严重的话。
So it is possible that the events and conditions that led to the rise of life on Earth are not quite as extraordinary as we like to think. Still, they were extraordinary enough, and one thing is certain: they will have to do until we find some better.
因此，导致地球上出现生命的事件和条件很可能不像你乐意认为的那样很不寻常。不过，它们还是很不寻常的。有一点是肯定的：在找到更好的理由之前，我们只能说它们是很不寻常的。