Galileo Galilei

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.

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

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.

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

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.

By denying scientific principles, one may maintain any paradox.

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

Surely it is a great thing to increase the numerous host of fixed stars previously visible to the unaided vision, adding countless more which have never before been seen, exposing these plainly to the eye in numbers ten times exceeding the old and familiar stars.

If the Earth were not subject to any change I would consider the Earth a big but useless body in universe, paralyzed...superfluous and unnatural.Those who so exalt incorruptibility, unchangeability and the like, are, I think, reduced to saying such things both because of inordinate desire they have to live for a long time and because of the terror they have of death...they do not realize that if men were immortal, they would have never come into the world.

The sun, with all the 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.

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