The dynamic law of attraction and reaction needed only a Newton to fix it in algebraic form.

吸引力和反作用力的动态定律只需要一个牛顿就可以将其固定为代数形式。

If the student means to try the experiment of framing a dynamic law, he must assign values to the forces of attraction that caused the trouble; and in this case he has them in plain evidence.

如果学生打算尝试构建动态定律的实验，他必须给引起麻烦的吸引力赋值；在这种情况下，他有明显的证据。

A dynamic law requires that two masses — nature and man — must go on, reacting upon each other, without stop, as the sun and a comet react on each other, and that any appearance of stoppage is illusive.

动力法则要求两个群体——自然和人——必须持续不断地相互反应，就像太阳和彗星相互反应一样，任何停止的现象都是虚幻的。