Darkness would not leave its natural Domain as Mani taught.

But if they talk foolishly against these things, against all propriety they are debating so that only those things that are not proper may be proclaimed. And if they are thus puffed up though in Error (it is) as if they had found out something true ; for it has escaped the notice of the Heretics that they have discovered (only) Error; but they by their Freewill have been discovered [P. 40, l.10.] by it according to its will. And because of the proud who have exalted themselves, let us diverge (lit., creep) a little from our Examination, and let us disregard them on the one side that they may be defeated rightly on the other. For it would never be pleasant for the Darkness to depart from its Domain, because every Entity which exists is contented if it is in its own place—because that is the place which belongs to its nature—[See from illustrations that this is true.] as fish are in water, as moles in sepulchral vaults,8 as moths in clothing, as worms in wood, as maggots in barns, as swallows in places frequented by man, as an owl in ruins, as a dove in the light, and as bats in the night. To these and many others their natural dwelling-place is pleasant, and if any one changes the dwelling-places which belong to them for those which do not belong to them, that is to say, places which hurt them instead of those [P. 41.] which do not hurt them, it is a great evil and bitter trouble for them as the celebrated Psalm of the Blessed David reckons ; and he declares in due order the places of all of them in Psalm civ, which is 'Bless the Lord, O my Soul, O Lord my God, thou art become very great,' which declares that according to their nature are their places, and according to their places is their contentment. For if you immersed a fish in oil, and hid a mole in honey, and made a moth live in silver, or worms in gold, or a louse in a heap of pearls, although these excel the dwelling-places [lxix] which belong to them, yet they are contented with their own (dwelling-place). And if these things that are made, and that are not Entities are contented with the places which were created for them, how much more is the Entity of Darkness contented with its natural den! And if any one stimulates it to go forth thence, it suffers pain, just as a man pains the dark mole when he brings it up from its dark place.