"One other lesson needs to be drawn explicitly. A project is not a house of cards which collapses when a single "key" person is removed. At least, it should not be; but often, when management thinks it is, the prophecy becomes self-fulfilling. That was one of the lessons in Mark's case, for if a little less reliance had been placed upon Mark, his manager might have populated his team with other than trainees. After all, even if the "key" man is as contented as a cow with his work, people are sometimes inconsiderate enough of their managers to get sick, to get drafted, or to die. No, if a manager wants to run a stable project, he would do well to follow this simple maxim: If a programmer is indispensable, get rid of him as quickly as possible."

"The Psychology of Computer Programming", Gerald M. Weinberg