I can calculate the motion of heavenly bodies, but not the madness of people.

My principal method for defeating error and heresy is by establishing the truth. One purposes to fill a bushel with tares, but if I can fill it first with wheat, I may defy his attempts.

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.

The great ocean of truth lay all undiscovered before me.

To every action there is always opposed an equal reaction.

This thing is but a puny imitation of a much grander system whose laws you know, and I am not able to convince you that this mere toy is without a designer or maker; yet you profess to believe that the great original from which the design is taken has come into being without either designer or maker! Now tell me by what sort of reasoning do you reach such an incongruous conclusion?

We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.