translation.en: But while we know a great deal more about sleep now than when Galen was around, we still haven't understood why it is that sleep, of all of our activities, has this incredible restorative function for the mind.
translation.zh: 我们现在对睡眠的了解 比伽林那个时期多了很多 但是我们仍然不知道 为什么在我们所有的活动中，只有睡眠 有如此这般可以促使我们 头脑变得清晰的功能