Top 143 Quotes & Sayings by Galileo Galilei

We must say that there are as many squares as there are numbers.

It vexes me when they would constrain science by the authority of the Scriptures, and yet do not consider themselves bound to answer reason and experiment.

I think that in the discussion of natural problems we ought to begin not with the Scriptures, but with experiments, and demonstrations.

Who would set a limit to the mind of man? Who would dare assert that we know all there is to be known?

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.

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

The nature of the human mind is such that unless it is stimulated by images of things acting upon it from without, all remembrance of them passes easily away.

If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.

I give infinite thanks to God, who has been pleased to make me the first observer of marvelous things.

It is surely harmful to souls to make it a heresy to believe what is proved.

By denying scientific principles, one may maintain any paradox.

Nature is relentless and unchangeable, and it is indifferent as to whether its hidden reasons and actions are understandable to man or not.

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

The Milky Way is nothing else but a mass of innumerable stars planted together in clusters.

Facts which at first seem improbable will, even on scant explanation, drop the cloak which has hidden them and stand forth in naked and simple beauty.

I notice that young men go to the universities in order to become doctors or philosophers or anything, so long as it is a title, and that many go in for those professions who are utterly unfit for them, while others who would be very competent are prevented by business or their daily cares, which keep them away from letters.

Where the senses fail us, reason must step in.

He who looks the higher is the more highly distinguished, and turning over the great book of nature (which is the proper object of philosophy) is the way to elevate one's gaze.

We cannot teach people anything; we can only help them discover it within themselves.

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

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.

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

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed.

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

And yet it moves.

The vain presumption of understanding everything can have no other basis than never having understood anything. For anyone who had ever experienced just once the perfect understanding of one single thing, and had truly tasted how knowledge is accomplished, would recognize that of the infinity of other truths he understands nothing.

With regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them.

The greatest wisdom is to get to know oneself.

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.

Scripture is a book about going to Heaven. It's not a book about how the heavens go.

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

The prohibition of science would be contrary to the Bible, which in hundreds of places teaches us how the greatness and the glory of God shine forth marvelously in all His works, and is to be read above all in the open book of the heavens.

Nonetheless, it moves.

The deeper I go in considering the vanities of popular reasoning, the lighter and more foolish I find them. What greater stupidity can be imagined than that of calling jewels, silver, and gold "precious," and earth and soil "base"?

There are those who reason well, but they are greatly outnumbered by those who reason badly.

Wine is sunlight, held together by water.

You cannot teach a person something he does not already know, you can only bring what he does know to his awareness.

You may force me to say what you wish; you may revile me for saying what I do. But it moves.

Measure what can be measured, and make measureable what cannot be measured.

To understand the Universe, you must understand the language in which it's written, the language of Mathematics.

Two truths cannot contradict one another.

The laws of nature are written by the hand of God in the language of mathematics.

In my studies of astronomy and philosophy I hold this opinion about the universe, that the Sun remains fixed in the centre of the circle of heavenly bodies, without changing its place; and the Earth, turning upon itself, moves round the Sun.

God is known by nature in his works, and by doctrine in his revealed word.

They who depend upon manifest observations will philosophize better than those who persist in opinions repugnant to the senses.

I am inclined to think that the authority of Holy Scripture is intended to convince men of those truths which are necessary for their salvation, which, being far above man's understanding, can not be made credible by any learning, or any other means than revelation by the Holy Spirit.

Nothing can be taught to a man, only it's possibly to help him to discover it inside.

Mathematics is the key and door to the sciences.

Nothing occurs contrary to nature except the impossible, and that never occurs.

It seems to me that it was well said by Madama Serenissima, and insisted on by your reverence, that the Holy Scripture cannot err, and that the decrees therein contained are absolutely true and inviolable. But I should have in your place added that, though Scripture cannot err, its expounders and interpreters are liable to err in many ways; and one error in particular would be most grave and most frequent, if we always stopped short at the literal signification of the words.

Knowing thyself, that is the greatest wisdom.

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.

To be humane, we must ever be ready to pronounce that wise, ingenious and modest statement 'I do not know'.

Who would dare assert that we know all there is to be known?

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

See now the power of truth.

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

You can't teach anybody anything, only make them realize the answers are already inside them.

And who can doubt that it will lead to the worst disorders when minds created free by God are compelled to submit slavishly to an outside will? When we are told to deny our senses and subject them to the whim of others? When people devoid of whatsoever competence are made judges over experts and are granted authority to treat them as they please? These are the novelties which are apt to bring about the ruin of commonwealths and the subversion of the state.

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