As W.B. Yeats continued to write the stories of faery, he also continued to question the true nature of the entities and spirits of these encounters. The evolution of wood spirit or green man into the devil is a well documented development and narrative of the church. Clearly, in this story from his book Celtic Twilight, Yeats was not entirely convinced.
My old Mayo woman told me one day that something very bad had come down the road and gone into the house opposite, and though she would not say what it was, I knew quite well. Another day she told me of two friends of hers who had been made love to by one whom they believed to be the devil. One of them was standing by the road-side when he came by on horseback, and asked her to mount up behind him, and go riding. When she would not he vanished. The other was out on the road late at night waiting for her young man, when something came flapping and rolling along the road up to her feet. It had the likeness of a newspaper, and presently it flapped up into her face, and she knew by the size of it that it was the Irish Times. All of a sudden it changed into a young man, who asked her to go walking with him. She would not, and he vanished.
I know of an old man too, on the slopes of Ben Bulben, who found the devil ringing a bell under his bed, and he went off and stole the chapel bell and rang him out. It may be that this, like the others, was not the devil at all, but some poor wood spirit whose cloven feet had got him into trouble.