“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.”

“I esteem myself happy to have as great an ally as you in my search for truth.”

“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?”

“The modern observations deprive all former writers of any authority, since if they had seen what we see, they would have judged as we judge.”

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

“If I were again beginning my studies, I should follow the advice of Plato and start with mathematics, a science which proceeds very cautiously and admits nothing as established until it has been rigidly demonstrated.”

“Geometry was invented that we might expeditiously avoid, by drawing Lines, the Tediousness of Computation.”

“I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses; for whatever is not deduced from the phenomena is to be called a hypothesis, and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy.”

“Experience never errs; it is only your judgments that err by promising themselves effects such as are not caused by your experiments.”

“There is a fundamental difference between religion, which is based on authority and science, which is based on observation and reason. Science will win, because it works.”

“My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.”

“I think I can safely say that nobody understands quantum mechanics.”