Gian Carlo Rota’s Indiscrete Thoughts is a must-read for every budding mathematician. He’s highly opinionated and among articles like “Ten things I should have learnt as a graduate student”, one can also find short biographies of biggies like Emil Artin, Stan Ulam and Solomon Lefshetz. Below is a paragraph taken from the book.

His advisor Jack Schwartz gives Rota the task of cleaning up the tome “Linear Operators” by Dunford – Schwartz for errors, solving exercises, correcting semicolons etc. Here is Rota’s description about one of the questions he wasn’t able to solve.

It took me half the summer to finish checking the problems in Chapter Three. There were a few that I had trouble with, and worst of all, I was unable to work out Problem Twenty of Section Nine. One evening Dunford and several other members of the group got together to discuss changes in the exercises. Jack was in New York City. It was a warm summer evening and we sat on the hard wooden chairs of the corner office of Leet Oliver Hall. Pleasant sounds of squawking crickets and frogs along with mosquitoes came through the open gothic windows. After I admitted my failure to work out Problem Twenty, Dunford tried one trick after another on the blackboard in an effort to solve the problem or to find a counterexample. No one remembered where the problem came from, or who had inserted it.

After a few hours, feeling somewhat downcast, we all got up and left. The next morning I met Jack, who patted me on the back and told me, “Don’t worry, I could not do it either.” I did not hear about Problem Twenty of Section Nine for another three years. A first-year graduate student had taken Dunford’s course in linear operators. Dunford had assigned him the problem, the student solved it, and developed an elegant theory around it. His name is Robert Langlands.