Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion.

Where both are friends, it is right to prefer truth.

...from the same principles, I now demonstrate the frame of the System of the World.

Trials are medicines which our gracious and wise Physician prescribes because we need them; and he proportions the frequency and weight of them to what the case requires. Let us trust his skill and thank him for his prescription.

As in Mathematicks, so in Natural Philosophy, the Investigation of difficult Things by the Method of Analysis, ought ever to precede the Method of Composition. This Analysis consists in making Experiments and Observations, and in drawing general Conclusions from them by Induction, and admitting of no Objections against the Conclusions, but such as are taken from Experiments, or other certain Truths. For Hypotheses are not to be regarded in experimental Philosophy.

To explain all nature is too difficult a task for any one man or even for any one age

To every action there is always opposed an equal reaction.