Nods, "The Unforgivables are those spells which are undoubly dark and cannot be argued about on their nature. But on the other hand, there are some dark spells that only become dark on the intention alone. A petrification charm, for example, which can be used for defensive purpose only can change its nature ot dark, almost fatal magic. That makes the nature of some spell so argued about. However, again, the Unforgivables cannot be argued about. Only spells which are and will always be dark."