Science is about understanding the world, and medicine is about applying that understanding to help people.

译文：昨天还看见花开，今天就看见花落。花开花落本是无情的自然规律，别怪夜里风雨太狠——人生也是这样无常。

解释：处于安全环境时要考虑到可能出现的危险，考虑到危险就会有所准备，事先有了准备就可以避免祸患。