There was a time when rumors began to reach Master Foo and his students of a prodigiously gifted programmer, a young man who wandered the length and breadth of the land performing mighty feats of coding and humiliating all who dared set their skill against his.

Eventually this prodigy came to visit Master Foo, who received him politely and offered him tea. The Prodigy accepted with equal politeness and explained the motive for his visit.

“I have come to you,” he said “seeking a code and design review of my latest project. For it is of surpassing complexity, and I do not have peers capable of understanding it. Only an acknowledged master such as yourself (and here the Prodigy bowed deeply) can have the discernment required.”

Master Foo bowed politely in return and began examining the Prodigy's code. After some time he raised his eyes from the screen. “This code is at first sight very impressive,” he said. “It is elegant in design, utilizing original algorithms of great ingenuity, and appears to be implemented in a craftsmanlike way which minimizes the possibility of errors.”

The Prodigy looked very pleased at this praise, but Master Foo continued: “However, I detect one significant flaw.”

“Flaw?” the Prodigy said. “What flaw?”

“This code is difficult to read,” said Master Foo. “It is only thinly commented, its invariants are not specified, and I see no narrative description of its architecture or internal data structures anywhere. These problems will seriously impede your cooperation with other programmers.”

The Prodigy drew himself up haughtily. “I do not seek the cooperation of other programmers,” he said. “Every time I thought I had found one who might match me in skill I have been disappointed. Thus, I work alone.”

“But even the hacker who works alone,” said Master Foo, “collaborates with others, and must constantly communicate clearly to them, lest his work become confused and lost.”

“Of what others do you speak?” the Prodigy demanded.

Master Foo said: “All your future selves.”

Upon hearing this, the Prodigy was enlightened.