"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."

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

"Mathematics is the key and door to the sciences."

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

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

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

"The greatest wisdom is to get to know oneself."

"Passion is the genesis of genius."

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

"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."

"The number of people that can reason well is much smaller than those that can reason badly. If reasoning were like hauling rocks, then several reasoners might be better than one. But reasoning isn't like hauling rocks, it's like, it's like racing, where a single, galloping Barbary steed easily outruns a hundred wagon-pulling horses."

"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]."

"Wine is sunlight, held together by water."

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

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

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

"Measure what can be measured, and make measurable what cannot be measured."

"In regard to the philosophers, if they be true philosophers, i.e., lovers of truth, they should not be irritated that the earth moves. Rather, if they realize that they have held a false belief, they should thank those have shown them the truth; and if their opinion stands firm that the earth doesn't move, they will have reason to boast than be angered."

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

"By denying scientific principles, one may maintain any paradox."

"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."

"Who indeed will set bounds to human ingenuity? Who will assert that everything in the universe capable of being perceived is already discovered and known?"

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

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

"Names and attributes must be accommodated to the essence of things, and not the essence to the names, since things come first and names afterwards."

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

"They seemed to forget that the increase of known truths stimulates the investigation, establishment and growth of the arts; not their dimination or destruction."

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

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

"(T)he increase of known truths stimulates the investigation, establishment, and growth of the arts."

"Mathematics is the language in which God has written the universe"

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

"In the future, there will be opened a gateway and a road to a large and excellent science into which minds more piercing than mine shall penetrate to recesses still deeper."

"E pur si muove. (It still moves.) (What Galileo purportedly muttered after torturers forced him to recant his theory that the earth orbits the sun.)"

"The sun with all the planets around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the Universe to do."

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

"And, believe me, if I were again beginning my studies, I should follow the advice of Plato and start with mathematics."

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

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

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

"To me, a great ineptitude exists on the part of those who would have it that God made the universe more in proportion to the small capacity of their reason than to His immense, His infinite, power."

"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."

"Anyone who thinks sitting in church can make you a Christian must also think that sitting in a garage can make you a car."

"Cats are intended to teach us that not everything in nature has a purpose."

"A book is a gift you can open again and again."

"Nothing you do for children is ever wasted."

"I believe in looking reality straight in the eye and denying it."

"When in doubt, look intelligent."

"Thank you, dear God, for this good life and forgive us if we do not love it enough."

"You get old and you realize there are no answers, just stories."