Terry Pratchett: Equal Rites

The entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks.

If you ignore the rules people will, half the time, quietly rewrite them so that they don`t apply to you.

It is well known that a vital ingredient of success is not knowing that what you're attempting can't be done. A person ignorant of the possibility of failure can be a halfbrick in the path of the bicycle of history.