把这一句，留给此刻的你

To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.

对于每一个动作，总是有一个对立的相等的反应，或者，两个物体相互作用，总是相等的，并且指向相反的部分。

— Sir Isaac Newton 牛顿