"To be a mathematician you must love mathematics more than family, religion, money, comfort, pleasure, glory. I do not mean that you must love it to the exclusion of family, religion, and the rest, and I do not mean that if you do love it, you'll never have any doubts, you'll never be discouraged, you'll never be ready to chuck it all and take up gardening instead. Doubts and discouragements are part of life. Great mathematicians have doubts and get discouraged, but usually they can’t stop doing mathematics anyway, and, when they do, they miss it very deeply. [...] Mind you, I am not recommending or insisting that you love mathematics. I am not issuing an order: “If you want to be a mathematician, start loving mathematics forthwith”—that would be absurd. What I am saying is that the love of mathematics is a hypothesis without which the conclusion doesn’t follow. If you want to be a mathematician, look into your soul and ask yourself how much you want to be one. If the wish isn’t very deep and very great, if it is not, in fact, maximal, if you have another desire that takes precedence, or even more than one, then you should not try to be a mathematician. The “should” is not a moral one; it is a pragmatic one. I think that you would probably not succeed in your attempt, and, in any event, you would probably feel frustrated and unhappy."