Poor little toads of the Medieval period, getting stuck with horrid associations of despicable things — putrefaction, death, and lust. And did you notice how all three of those adjectives were lumped together? That’s because the Christian Church at the time intentionally set about trying to make carnality associated with disgusting things, because church doctrine taught that celibacy was the purest and most Godlike state.
And so, the downtrodden toad got besmirched as the ambassadors of things both decaying and lusty. In these three images, you see Romanesque sculptures of a figure known as “Frau Welt” or “Ms. World” (with the masculine Fürst der Welt in the third slide), which is beautiful and youthful up front (that’s the temptation part), but studded with toads (and also snakes) from behind.
Some of the negative associations come from the Bible’s Book of Revelation, 16:13: “and I saw three unclean spirits like frogs come out of the mouth of the dragon, and our of the mouth of the beast, and out of the mouth of the false prophet”.
Then there are religious writings of mystics who saw visions of toads combined with sexuality in gross ways. One 14th-century writer called Jean Gobi wrote of a woman who died after committing adultery with a relative who was tormented in the afterlife by toads upon her eyes that punished her for her “luxurious glances”. The visionary Christina of Stommeln suffered from demonic torture when she lay in bed at prayer: mystical devil toads climbed under her dress and lay on her chest for days before she excised them. And the devout (and maybe mentally ill) Ermine de Reims dealt with demonic toads that lay on her face and moved in between her thighs before leaving her to sleep with “very ugly [ie, sexual] dreams”.
Making decay, toads, and lust fit into the same category was an association fallacy that the Church successfully promoted for a very long time.
Source: _The Strange Case of Ermine de Reims_, Renate Blumenfeld-Kosinski, Univ of Penn Press, 2015, pp 117-118. Atlas Obscura “Why figures swarmed with toads lurk on Middle Ages cathedrals,” Elizabeth Harper, July 24, 2014. Cathedral of Worms (slide one)