**Paul Erdős** (26 March 1913 – 20 September 1996) was a Hungarian mathematician. Erdős published more papers than any other mathematician in history, working with hundreds of collaborators. He worked on problems in combinatorics, graph theory, number theory, classical analysis, approximation theory, set theory, and probability theory. He is also known for his “legendarily eccentric” personality.

He had his own idiosyncratic vocabulary: he spoke of “The Book”, an imaginary book in which God had written down the best and most elegant proofs for mathematical theorems. Lecturing in 1985 he said, “You don’t have to believe in God, but you should believe in *The Book*.” He himself doubted the existence of God, whom he called the “Supreme Fascist” (SF). He accused the SF of hiding his socks and Hungarian passports, and of keeping the most elegant mathematical proofs to himself. When he saw a particularly beautiful mathematical proof he would exclaim, “This one’s from *The Book*!”. This later inspired a book entitled *Proofs from THE BOOK*.

Other idiosyncratic elements of Erdős’ vocabulary include:

- Children were referred to as “epsilons” (because in mathematics, particularly calculus, an arbitrarily small positive quantity is commonly denoted by that Greek letter ε
- Women were “bosses”;
- Men were “slaves”;
- People who stopped doing math had “died”;
- People who physically died had “left”;
- Alcoholic drinks were “poison”;
- Music was “noise”;
- People who had married were “captured”;
- People who had divorced were “liberated”;
- To give a mathematical lecture was “to preach” and
- To give an oral exam to a student was “to torture” him/her.