He who hid well, lived well.

Doubt is the origin of wisdom

I can doubt everything, except one thing, and that is the very fact that I doubt. Simply put - I think, therefore I am

Wonder is the first of all the passions.

Bad books engender bad habits, but bad habits engender good books.

I accept no principles of physics which are not also accepted in mathematics.

Truths are more likely to be discovered by one man than by a nation