Galileo Galilei Quotes

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

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

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 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.

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

Knowing thyself, that is the greatest wisdom.

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

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

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

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

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

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

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.

Two truths cannot contradict one another.

Nonetheless, it moves.

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

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.

Long experience has taught me this about the status of mankind with regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them, while on the other hand to know and understand a multitude of things renders men cautious in passing judgment upon anything new.

Where the senses fail us, reason must step in.

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

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

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

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

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

The greatest wisdom is to get to know oneself.

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.

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.

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

I wish, my dear Kepler, that we could have a good laugh together at the extraordinary stupidity of the mob. What do you think of the foremost philosophers of this University? In spite of my oft-repeated efforts and invitations, they have refused, with the obstinacy of a glutted adder, to look at the planets or the Moon or my glass [telescope].

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

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"?

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

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.

In the long run my observations have convinced me that some men, reasoning preposterously, first establish some conclusion in their minds which, either because of its being their own or because of their having received it from some person who has their entire confidence, impresses them so deeply that one finds it impossible ever to get it out of their heads.

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

Mathematics is the key and door to the sciences.

Surely, God could have caused birds to fly with their bones made of solid gold, with their veins full of quicksilver, with their flesh heavier than lead, and with their wings exceedingly small. He did not, and that ought to show something. It is only in order to shield your ignorance that you put the Lord at every turn to the refuge of a miracle.

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

Holy Scripture could never lie or err...its decrees are of absolute and inviolable truth.

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

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.

It is very pious to say and prudent to affirm that the holy Bible can never speak untruth -- whenever its true meaning is understood. But I believe nobody will deny that it is often very abstruse, and may say things which are quite different from wha.

And believe me, if I were again beginning my studies, I should follow the advice of Plato and start with the mathematical sciences, which proceed very cautiously and admit nothing as established until it has been rigorously demonstrated.

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?

Wine is sunlight, held together by water.

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

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

I do not think it is necessary to believe that the same God who has given us our senses, reason, and intelligence wished us to abandon their use, giving us by some other means the information that we could gain through them.

We see only the simple motion of descent, since that other circular one common to the Earth, the tower, and ourselves remains imperceptible. There remains perceptible to us only that of the stone, which is not shared by us; and, because of this, sense shows it as by a straight line, always parallel to the tower, which is built upright and perpendicular upon the terrestrial surface.

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