Mathematics is an interesting intellectual sport but it should not be allowed to stand in the way of obtaining sensible information about physical processes.
Quoted in N Rose Mathematical Maxims and Minims (Raleigh N C 1988).
The purpose of computing is insight, not numbers.
It is better to do the right problem the wrong way than the wrong problem the right way.
If you don't work on important problems, it's not likely that you'll do important work.