A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?" The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

-- Geoffrey James
The Tao of Programing