Violinist Georges Enesco was saddled with a poor pupil who eventually wanted to give a recital. Enesco agreed to accompany him on the piano but realized at the last minute that he needed a page turner. He prevailed on Alfred Cortot, who was sitting in the audience. A review the next morning read:

“There was a most remarkable concert last night at the Salle Pleyel. The man who should have been playing the violin was playing the piano, the man who should have been playing the piano was turning the pages, and the man who should have been turning the pages was playing the violin.”

(Likewise: “It is a maxim among practical statisticians that ‘The data you need are not the data you have, the data you have are not the data you want, and the data you want are not the data you need.'” — T.W. Körner, The Pleasures of Counting, 1996)