Milan Kundera mentioned, by the way, in his “The Unbearable Lightness of Being” that Johannes Scotus Erigena, the great ninth-century theologian … believed … that Adam’s virile member could be made to rise like an arm or a leg, when and as its owner wished. I decided to check this information.
Johannes Scotus Eriugena (c. 815–877) (John The Scot), was an Irish theologian and Neoplatonist philosopher. The name Erigena means the same as Scotus, ‘born in Ireland‘. Bertrand Russell called him ‘the most astonishing figure of the early Medieval period‘. His magnum opus De divisione naturae (“The division of nature”, also titled Periphyseon) was probably completed around 866-867 and consisted of five books. The Division of Nature has been called the final achievement of ancient philosophy, a work which “synthesizes the philosophical accomplishments of fifteen centuries.” In 1225 his works were condemned as heretical. In 1681 ‘De divisione naturae’ was rediscovered at Oxford University and immediately placed on the ‘Index of Forbidden Books‘. In that work Eriugena, indeed, supposed that Adam could use his sexual organs, like all the others in his body, by mere willpower and without excitement or ardor.
Despite the later condemnation of heresy, in this aspect, Erigena definitely has caught the mood of the epoch. His ideas about sexual conjunction in tranquillity of body and soul and without corrupting virginity make an impression because sound like symptoms of the serious mental illness of the whole generation. But I think this concept has a non-sexual aspect as well.
If you don’t control the parts of you body it means that they are controlled by someone else. You should hide them because they are spoiled by malicious forces! There is only a short way from these ideas to a belief that nudity is evil.
But we are too much under the influence of medieval demonology. It is difficult for us to understand that in the New Testament there is no general idea of the devil. There is the idea of evil, the idea of temptation, the idea of demons; there is Satan who tempted Jesus; but all these are quite different ideas, that is, separate and distinct from one another, always allegorical and very far from the medieval conception of the devil.