Via The Glittering Eye, a historical reminder: today is the anniversary of the birth of Ulysses S. Grant, consecutively drunken failure, commander of the Federal armies in the latter stages of the American Civil War, and President. He was extremely good at being a drunken failure, which would normally have disqualified him from any higher post.
War brings odd opportunities, and Grant turned out to have a way to win the war when a succession of apparently smarter men (think McClellan, Hooker) had failed. Grant's life always seemed to me to argue against the logic of the rich man in the parable of the talents: being capable in one job doesn't mean being capable the next rung up the ladder. What is odder, being inept at following doesn't need to mean being hopeless at leading.