The Catholic Encyclopedia has a good article on this, but it was written a hundred years ago, so isn't quite up to date.
www.thebookshelfinmylivingroom.ie
( Dr Preference AjcuiVd289, Wed 10 Jun 2009, 12:55, archived)

Was that a real URL?
I'm never sure these days.
( Bats, Wed 10 Jun 2009, 13:01, archived)

Oh dear.

( Dr Preference AjcuiVd289, Wed 10 Jun 2009, 13:01, archived)

Sorry :(

( Bats, Wed 10 Jun 2009, 13:03, archived)