“We see only the simple motion of descent, since that other circular one common to the Earth, the tower, and ourselves remains imperceptible.”

I’ve loved the stars too fondly to be fearful of the night.

The greatest wisdom is to get to know oneself.

I have never met a man so ignorant that I couldn’t learn something from him.

In the sciences, the authority of thousands of opinions is not worth as much as one tiny spark of reason in an individual man.

Mathematics is the key and door to the sciences.

The sun, with all those planets revolving around it and dependent on it, can still ripen a bunch of grapes as if it had nothing else in the universe to do.

Nature does not act by means of many things when it can do so by means of a few.

It is a beautiful and delightful sight to behold the body of the Moon.

The deeper I go in considering the vanities of popular reasoning, the lighter and more foolish I find them.

Passion is the genesis of genius.

Earth, turning upon itself, moves round the Sun.

I do not feel obliged to believe that the same God who has endowed us with senses, reason, and intellect has intended us to forego their use.

You cannot teach a man anything, you can only help him find it within himself.

All truths are easy to understand once they are discovered; the point is to discover them.

Two truths cannot contradict one another.

I am certainly interested in a tribunal in which, for having used my reason, I was deemed little less than a heretic.