"...By the end of August, I was mentally drained, more drained, I think, than I had ever been. The creative potential, the capacity to solve problems, changes in a man in ebbs and flows, and over this he has little control. I had learned to apply a kind of test. I would read my own articles, those I considered the best. If I noticed in them lapses, gaps, if I saw that the thing could have been done better, my experiment was successful. If, however, I found myself reading with admiration, that meant I was in trouble."

His Master's Voice, Stanislaw Lem; p. 106 from the Northwestern University Press 3rd edition, 1999