Innovation comes from solving real problems.
The night is a great teacher, but the stars are its lessons.
"The past is always carried into the present by small things."
解释:在人活动范围内的水就污浊,在野外无人地方的水就清洁。同为一样的水,都是从天边开源,有的混浊有的清洁,这是它们所处环境使它们这样的。