What is hardest of all? That which seems most simple: to see with your eyes what is before your eyes.

Mathematicians are like Frenchmen: whatever you say to them they translate into their own language and forthwith it is something entirely different.

The hardest thing to see is what is in front of your eyes.

Everyone believes in his youth that the world really began with him, and that all merely exists for his sake.

The most congenial social occasions are those ruled by cheerful deference of each for all.

The solution of every problem is another problem

Oh how sweet it is to hear one's own convictions from another's lips.