Or take the following, from J. H. Roberts' essay, as given in Welsh in Edwards' Cymru for 1897, p. 190: it reminds one of an ordinary fairy tale, but it is not quite like any other which I happen to know:--In the western end of the Arennig Fawr there is a cave: in fact there are several caves there, and some of them are very large too; but there is one to which the finger of tradition points as an ancient abode of the Tylwyth Teg. About two generations ago, the shepherds of that country used to be enchanted by one of them called Mary, who was remarkable for her beauty. Many an effort was made to catch her or to meet her face to face, but without success, as she was too quick on her feet. She used to show herself day after day, and she might be seen, with her little harp, climbing the bare slopes of the mountain. In misty weather when the days were longest in summer, the music she made used to be wafted by the breeze to the ears of the love-sick shepherds. Many a time had the boys of the Filltir Gerrig heard sweet singing when passing the cave in the full light of day, but they were subject to some spell, so that they never ventured to enter. But the shepherd of Boch y Rhaiadr had a better view of the fairies one Allhallows night (ryw noson Calangaeaf) when returning home from a merry-making at Amnod. On the sward in front of the cave what should he see but scores of the Tylwyth Teg singing and dancing! He never saw another assembly in his life so fair, and great was the trouble he had to resist being drawn into their circles.
Let us now come to the treasure caves, and begin with Ogof Arthur, 'Arthur's Cave,' in the southern side of Mynyd y Cnwc [49] in the parish of Llangwyfan, on the south-western coast of Anglesey. The foot of Mynyd y Cnwc is washed by the sea, and the mouth of the cave is closed by its waters at high tide, but the cave, which is spacious, has a vent-hole in the side of the mountain [50]. So it is at any rate reported in the Brython for 1859, p. 138, by a writer who explored the place, though not to the end of the mile which it is said to measure in length. He mentions a local tradition, that it contains various treasures, and that it temporarily afforded Arthur shelter in the course of his wars with the Gwydelod or Goidels. But he describes also a cromlech on the top of Mynyd y Cnwc, around which there was a circle of stones, while within the latter there lies buried, it is believed, an iron chest full of ancient gold. Various attempts are said to have been made by the more greedy of the neighbouring inhabitants to dig it up, but they have always been frightened away by portents. Here then the guardians of the treasure are creatures of a supernatural kind, as in many other instances, and especially that of Dinas Emrys to be mentioned presently.