Expressed egotism is, of course, no reason necessarily to disregard someone's work, but it is a warning signal. If someone can evaluate his work so poorly, is the work itself likely to be better? In many of his areas of intellectual interest, Popper's work is wanting. Hayek did more to advance Popper professionally early in his career than anyone else, and Popper remembered his personal debt to Hayek. Over the years, he wrote him a number of appreciative letters.