What a blessing it would be if we could open and shut our ears...as easily as we open and shut our eyes.

Diogenes, filthily attired, paced across the splendid carpets in Plato's dwelling. Thus, said he, do I trample on the pride of Plato. Yes, Plato replied, but only with another kind of pride.

The ordinary man is ruined by the flesh lusting against the spirit; the scholar by the spirit lusting too much against the flesh.

It is almost impossible to carry the torch of truth through a crowd without singeing somebody's beard.

I ceased in the year 1764 to believe that one can convince one’s opponents with arguments printed in books. It is not to do that, therefore, that I have taken up my pen, but merely so as to annoy them, and to bestow strength and courage on those on our own side, and to make it known to the others that they have not convinced us.

I am confident of my ability to demonstrate that one can sometimes believe in something and yet not believe in it. Nothing is less fathomable than the systems that motivate our actions.

All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty. They give me no pleasure. They are merely auxiliaries. At close range it is all not true.