Master Foo instructed his students:

“There is a line of dharma teaching, exemplified by the Patriarch McIlroy's mantra ‘Do one thing well’, which emphasizes that software partakes of the Unix way when it has simple and consistent behavior, with properties that can be readily modeled by the mind of the user and used by other programs.”

“But there is another line of dharma teaching, exemplified by the Patriarch Thompson's great mantra ‘When in doubt, use brute force’, and various sutras on the value of getting 90% of cases right now, rather than 100% later, which emphasizes robustness and simplicity of implementation.”

“Now tell me: which programs have the Unix nature?”

After a silence, Nubi observed:

“Master, these teachings may conflict.”

“A simple implementation is likely to lack logic for edge cases, such as resource exhaustion, or failure to close a race window, or a timeout during an uncompleted transaction.”

“When such edge cases occur, the behavior of the software will become irregular and difficult. Surely this is not the Way of Unix?”

Master Foo nodded in agreement.

“On the other hand, it is well known that fancy algorithms are brittle. Further, each attempt to cover an edge case tends to interact with both the program's central algorithms and the code covering other edge cases.”

“Thus, attempts to cover all edge cases in advance, guaranteeing ‘simplicity of description’, may in fact produce code that is overcomplicated and brittle or which, plagued by bugs, never ships at all. Surely this is not the Way of Unix?”

Master Foo nodded in agreement.

“What, then, is the proper dharma path?” asked Nubi.

The master spoke:

“When the eagle flies, does it forget that its feet have touched the ground? When the tiger lands upon its prey, does it forget its moment in the air? Three pounds of VAX!”

On hearing this, Nubi was enlightened.