Sed cum haec a spiritibus circa homines fiant, eam solam rerum imaginem fidelis anima non aspernatur, quae innocentiam relinquit incolumem. quod si materiam vitiis afferat, libidinem forte accendens aut avaritiam aut dominandi ingerens appetitum aut quicquid huiusmodi est ad subversionem animae, proculdubio aut caro aut spiritus malignus immittit, qui in quosdam exigentibus culpis, Domino permittente, tanta malitiae suae licentia debaccatur ut quod in spiritu patiuntur, miserrime et mendacissime credant in corporibus evenire. quale est quod noctilucam quandam vel Herodiadem vel praesidem noctis dominam concilia et conventus de nocte asserunt convocare, varia celebrari convivia, ministeriorum species diversis occupationibus exerceri, et nunc istos ad penam trahi pro meritis, nunc illos ad gloriam sullimari. praeterea infantes exponi lamiis et nunc frustratim discerptos edaci ingluvie in ventrem traiectos congeri, nunc praesidentis miseratione reiectos in cunas reponi. quis vel cecus hoc ludificantium demonum non videat esse nequitiam? quod vel ex eo patet, quod mulierculis et viris simplicioribus et infirmioribus in fide ista proveniunt. si vero quisquam eorum qui hac illusione laborat ab aliquo constanter et ex signis aliquibus arguatur, demonium statim aut superatur aut cedit et, ut dicitur, ex quo quis in luce arguitur, cessant opera tenebrarum. huius autem pestis cura efficacissima est ut fidem quis amplexus his mendaciis subtrahat mentis auditum et nequaquam respiciat ad huiusmodi vanitates et insanias falsas.
(John of Salisbury, Policraticus 2.17)
When spirits act thus in the case of human beings the devout soul should reject every image except that which leaves its innocence unimpaired. For should the dream add fuel to vice, perchance by inducing lust and avarice or by inspiring greed for dominion or anything of the sort to destroy the soul, undoubtedly it is the flesh or the evil spirit that sends it. This spirit, with the permission of the Lord because of their sins, wreaks its unbridled wickedness upon some men so violently that what they suffer in the spirit they wretchedly but falsely believe comes to pass in the flesh. For example it is said that some Moon or Herodias or Mistress of the Night calls together councils and assemblies, that banquets are held, that different kinds of rites are performed, and that some are dragged to punishment for their deeds and others raised to glory. Moreover babes are exposed to witches and at one time their mangled limbs are eagerly devoured, at another are flung back and restored to their cradles if the pity of her who presides is aroused. Cannot even the blind see that this is but the wickedness of mocking demons? This is quite apparent from the fact that it is for the weaker sex and for men of little strength or sense that they disport themselves in such a cult. If in fact anyone who suffers from such illusion is firmly censured by someone or by some sign the malign influence is either overcome or yields, and, as the saying is, as soon as one is censured in the light the works of darkness cease. The most effective cure however for this bane is for one to embrace the true faith, refuse to listen to such lies, and never to give thought to follies and inanities of the sort. (tr. Joseph B. Pike)