- VIII. Any non-trivial program contains at least one bug. -- Laws of Computer Programming
- Any non-trivial program contains at least one bug. Laws of Computer Programming, VIII
- Every interesting program has at least one variable, one branch, and one
loop.

.. and at least one bug!... - Every program has at least one bug and can be shortened by at least one instruction -- from which, by induction, one can deduce that every program can be reduced to one instruction which doesn't work.
- Every program has (at least) two purposes: the one for which it was written and another for which it wasn't.