Related:

• This principle is so perfectly general that no particular application of it is possible.
  -- Quoted by George Polya...
• wart n. A small, crocky feature that sticks out of an otherwise clean design.
  Something conspicuous for localized ugliness, especially a special-case exception to a general rule....
• wart: n. A small, {crock}y {feature} that sticks out of an otherwise {clean} design.
  Something conspicuous for localized ugliness, especially a special-case exception to a general rule....
• The real world is a special case. -- Horngren's Observation (generalized)
• For economists, the real world is often a special case.
• If If, Then Then. -- The Theorem Theorem
• If if, then then. -- The Theorem Theorem
• I am perfectly sane, and so am I.
• Sweer's Impossibility Theorem: Nothing can be both completely general and internally consistent at the same time.