All truths are easy to understand once they are discovered; the point is to discover them.
And yet it moves.
By denying scientific principles, one may maintain any paradox.
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 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.
I have never met a man so ignorant that I couldn’t learn something from him.
I think that in the discussion of natural problems we ought to begin not with the Scriptures, but with experiments, and demonstrations.
If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.
It is surely harmful to souls to make it a heresy to believe what is proved.
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.
Measure what is measurable, and make measurable what is not so.
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?
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.
Nature is relentless and unchangeable, and it is indifferent as to whether its hidden reasons and actions are understandable to man or not.
Philosophy is written in that great book which ever lies before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. This book is written in the mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth.
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.
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.
We cannot teach people anything; we can only help them discover it within themselves.
We must say that there are as many squares as there are numbers.
What has philosophy got to do with measuring anything? It’s the mathematicians you have to trust, and they measure the skies like we measure a field.
Where the senses fail us, reason must step in.