Galileo Galilei

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.

Mathematics is the language with which God has written the universe.

And yet it moves.

Philosophy is written in this grand book, the universe... It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it.

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

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

Measure what is measurable, and make measurable what is not so.

The book of nature is written in the language of mathematics.

Nature is written in mathematical language.

See now how the universe is composed of motions, and how these motions are connected.

The Bible shows the way to go to heaven, not the way the heavens go.

It is surely harmful to souls to make it a heresy to believe what the astronomers really and truly demonstrate.

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

Among the great men who have philosophized about this world, the most celebrated are Thales, Pythagoras, Empedocles, Anaxagoras, Anaximenes, Democritus, Parmenides, Heraclitus, Plato, Aristotle, Archimedes, and many others.

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.

The laws of Nature are written in the language of mathematics.

Doubt is the father of discovery.

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

He who only employs his mental effort in getting to know facts and phenomena will merely demonstrate some laws of nature, but never will he reach the final cause.