This may also be taken to refer to certain heretics or schismatics, or even to a bad Catholic, from whom at the time of his baptism the evil spirit had gone out. And he wanders about in dry places, that is, his crafty device is to try the hearts of the faithful, which have been purged of all unstable and transient knowledge, if he can plant in them any where the footsteps of his iniquity. But he says, I will return to my house whence I came out. And here we must beware lest the sin which we supposed extinguished in us, by our neglect overcome us unawares. But he finds his house swept and garnished, that is, purified by the grace of baptism from the stain of sin, yet replenished with no diligence in good works. By the seven evil spirits which he takes to himself, he signifies all the vices. And they are called more wicked, because he will have not only those vices which are opposed to the seven spiritual virtues, but also by his hypocrisy he will pretend to have the virtues themselves.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).