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

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

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

Wine is "light held together by moisture."

My dear Kepler, what would you say of the learned here, who, replete with the pertinacity of the asp, have steadfastly refused to cast a glance through the telescope? What shall we make of this? Shall we laugh, or shall we cry?

I never met a man so unknowledgeable, I could not learn something from him.

And yet it moves. About the earth, the comment he is rumored to have made after his recantation before the Inquisition.

See now the power of truth; the same experiment which at first glance seemed to show one thing, when more carefully examined, assures us of the contrary.

Alas! Your dear friend and servant Galileo has been for the last month hopelessly blind; so that this heaven, this earth, this universe, which I by my marvelous discoveries and clear demonstrations had enlarged a hundred thousand times beyond the belief of the wise men of bygone ages, henceforward for me is shrunk into such a small space as is filled by my own bodily sensations.

I have for many years been a partisan of the Copernican view because it reveals to me the causes of many natural phenomena that are entirely incomprehensible in the light of the generally accepted hypothesis. To refute the latter I have collected many proofs, but I do not publish them, because I am deterred by the fate of our teacher Copernicus who, although he had won immortal fame with a few, was ridiculed and condemned by countless people (for very great is the number of the stupid) Letter to Kepler

The great book of nature is written in mathematical symbols.

If you could see the earth illuminated when you were in a place as dark as night, it would look to you more splendid than the moon.

Mathematics is the key and door to the sciences.