All truths are easy to understand once they are discovered; the point is to discover them.
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.
Measure what is measurable, and make measurable what is not so.
Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed.
If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.
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.
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.