An excited student tells his math teacher. Sir, when I grow up I want to be the best mathematician in the world and for that I am not going to waste my time getting married or thinking about girls, only about mathematics.
The veteran math teacher replies: Nothing like that, when you're older, you'll get married and then it's very important that you have a lover. In this way, when your wife believes that you are with your lover and she believes that you are with your wife, you, to make maths.