Mark Twain once wrote something like "Cursing provides a release to the
soul denied even to prayer". In this spirit. profanity provides a level
of emotional release appropriate when stubbing your toe or knocking over
your 645 (Sorry, Paal). It can also be used deliberately to emphasize
a point or to invoke humor. The use of profanity changes dramatically
in the written word, however, and I don't think most people appreciate
that. Whether we like or not, if you just type what you would say it
has a very different impact on a reader than on a listener. The idea of
"spontaneous emotional content" just doesn't translate well since the
written word is more deliberate, even if it's just Email. The
deliberate use of profanity for serious emphasis (as opposed to just
shock) is much harder to achieve.
