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

The moon gravitates towards the earth and by the force of gravity is continually drawn off from a rectilinear motion and retained in its orbit.

We account the Scriptures of God to be the most sublime philosophy.

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.

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.

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.

Science, for me, gives a partial explanation for life. In so far as it goes, it is based on fact, experience and experiment.

The value and utility of any experiment are determined by the fitness of the material to the purpose for which it is used, and thus in the case before us it cannot be immaterial what plants are subjected to experiment and in what manner such experiment is conducted.

You must be ready to give up even the most attractive ideas when experiment shows them to be wrong.

Again the message to experimentalists is: Be sensible but don’t be impressed too much by negative arguments. If at all possible, try it and see what turns up. Theorists almost always dislike this sort of approach.

The art of drawing conclusions from experiments and observations consists in evaluating probabilities and in estimating whether they are sufficiently great or numerous enough to constitute proofs. This kind of calculation is more complicated and more difficult than it is commonly thought to be.

Experiments upon vegetation give reason to believe that light combines with certain parts of vegetables, and that the green of their leaves, and the various colors of flowers, is chiefly owing to this combination.

There is very little real liberty in the world; even those who seem freest are often the most tightly bound. Law, custom, public opinion, fear or shame make slaves of us all, as you will find when you try your experiment.

I have always been more interested in experiment, than in accomplishment.