Note 138 — Chapter VIII

'Consorting with them [the unclean spirits who have fallen from their first estate] and all use of their assistance is unlawful; much more any worship or veneration whatsoever. But a contemplation and knowledge of their nature, power, illusions, not only from passages of sacred scripture but from reason or experience, is not the least part of spiritual wisdom. So truly the Apostle, "We are not ignorant of his wiles." And it is not less permissible in theology to investigate the nature of demons, than in physics to investigate the nature of drugs, or in ethics the nature of vice.'—De Augmentis Scientiarum, lib. iii. 2.