Not so witty, but...

Here's from Pascal:

The more I see of men, the better I like my dog.

I have made this letter longer than usual because I lack the time to make it short.

Contradiction is not a sign of falsity, nor the lack of contradiction a sign of truth.

Reason's last step is the recognition that there are an infinite number of things which are beyond it.

The sole cause of man's unhappiness is that he does not know how to stay quietly in his room.

[I've been reading through Pascal cursorily because he's a source of inspiration for young Dorothea in Middlemarch.......Ah! These ice days off from school! What luxury!]