我们都被过去所困扰,过去总是存在的。
The worth of a mental process is in its service to life.
解析:自然的法则,是损减有余来补充不足;人类社会世俗的作法却不然,而是损减贫穷不足来供奉富贵有余。
The best way to learn mathematics is to do mathematics.