The writer is a man who has to live in the world but not be of it.
看着容易，要学会就很难；千万不要把容易得到的东西看得普通，就不知道珍惜。
控制的目的是使系统在存在不确定性和干扰的情况下仍能按期望的方式运行。
"The past is never dead. It's not even past."
最可持续的资源是人类的智慧。