396. However, in order to cast the light of reason on and so make clear what follows in this chapter, and the next chapters on free will, reformation and regeneration, etc., some preliminary remarks are needed, dealing with the will and the understanding, good and truth, love in general, the love of the world and self-love in particular, the external and internal man, and the purely natural and sensual man. This revelation is needed to prevent a rational person from having his ability to perceive the more remote consequences taken away as if by a fog, and as it were wrapped in fog running through the streets of a city, until he does not know his way home. For what use is theology without understanding? If the understanding is not enlightened when one is reading the Word, is it any more use than holding a lantern in the hand without the lamp lit, such as those in the hands of the five foolish virgins, who had no oil? So I will take up each subject in turn.