A manager asked a programmer how long it would take him to finish the
program on which he was working. "I will be finished tomorrow," the programmer
"I think you are being unrealistic," said the manager. "Truthfully,
how long will it take?"
The programmer thought for a moment. "I have some features that I wish
to add. This will take at least two weeks," he finally said.
"Even that is too much to expect," insisted the manager, "I will be
satisfied if you simply tell me when the program is complete."
The programmer agreed to this.
Several years later, the manager retired. On the way to his
retirement lunch, he discovered the programmer asleep at his terminal.
He had been programming all night.
- -- Geoffrey James, "The Tao of Programming"