30:  How do I turn on auto-fill mode by default?

  To turn on auto-fill mode just once for one buffer, use "M-x
  auto-fill-mode".

  To turn it on for every buffer in a certain mode, you must use the hook
  for that mode.  For example, to turn on auto-fill mode for all text
  buffers, including the following in your .emacs file:

    (add-hook 'text-mode-hook 'turn-on-auto-fill)

  If you want auto-fill mode on in all major modes, do this:

    (setq-default auto-fill-hook 'do-auto-fill)