Listening at the church-door in the dark, to hear shouted by a ghostly voice in the deserted edifice the names of those who are shortly to be buried in the adjoining churchyard, is a Hallow E'en custom in some parts of Wales. In other parts, the window serves the same purpose. There are said to be still extant, outside some village churches, steps which were constructed in order to enable the superstitious peasantry to climb to the window to listen. The principle of 'expectant attention,' so well known to physiological science, would be likely in this case to act with special force as a ghost-raiser. In an ancient MS. by Llywelyn Sion, of Llangewydd, there is mention of a frightful monster called the Fad Felen, which was seen through the key-hole of Rhos church by Maelgwn Gwynedd, who 'died in consequence.' This monster was predicted in a poem by Taliesin, as a 'strange creature' which should come from the sea marsh, with hair and teeth and eyes like gold. The yellow fever plague, which raged in Wales during some five years in the sixth century, is the monster referred to in this legend.