“It is reasonable that forces directed toward bodies depend on the nature and the quantity of matter of such bodies, as happens in the case of magnetic bodies.”

Therefore, the causes assigned to natural effects of the same kind must be, so far as possible, the same.

Physics, beware of metaphysics.

I feign no hypotheses.

Atheism is so senseless and odious to mankind that it never had many professors.

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.

Truth is ever to be found in the simplicity, and not in the multiplicity and confusion of things.

I keep the subject of my inquiry constantly before me, and wait till the first dawning opens gradually, by little and little, into a full and clear light.

The way to chastity is not to struggle directly with incontinent thoughts but to avert the thoughts by some imployment, or by reading, or meditating on other things.

The more time and devotion one spends in the worship of false gods, the less he is able to spend in that of the true One.

The instinct of brutes and insects can be the effect of nothing else than the wisdom and skill of a powerful ever-living agent.

No great discovery was ever made without a bold guess.

Truth is the offspring of silence and meditation.

I consider my greatest accomplishment to be lifelong celibacy.

It is the weight, not numbers of experiments that is to be regarded.

I have a fundamental belief in the Bible as the Word of God, written by those who were inspired. I study the Bible daily.

Nature is pleased with simplicity. And nature is no dummy.