

Never believe that anti-Semites are completely unaware of the absurdity of their replies. They know that their remarks are frivolous, open to challenge. But they are amusing themselves, for it is their adversary who is obliged to use words responsibly, since he believes in word. --Jean-Paul Sartre




In the history of mathematics, -1 was understood waaaay before 0.
For the Greeks, doing 1-1 would be invalid, something close to dividing by zero for us.