There are other accounts of this Trwyn sprite which credit it to a time long anterior to last century; but all are consistent in this, that the goblin is always invisible. The sole exception to this rule is the legend about its having once shown a white hand to some girls in the kitchen, thrusting it through the floor of its room overhead for that purpose. Now invisibility is a violation of fairy traditions, while ghosts are very often invisible--these rapping and stone-throwing ghosts, always. It might be urged that this spirit was a Bwbach, if a fairy at all, seeing that it kept pretty closely to the house; but on the whole I choose to class it among the inhabitants of the spirit-world; and really, the student of folk-lore must classify his materials distinctly in some understandable fashion, or go daft.