"From the Isles of Arran and the west continent often appears visible that enchanted island called O'Brasail and, in Irish, Beg Ara.
Whether it be real and firm land kept hidden by the special ordnance of God, or the terrestrial paradise, or else some illusion of airy clouds appearing on the surface of the sea, or the craft of evil spirits, is more than our judgments can pound out.
"There is now living, Murrough O'Ley, who imagines he was himself personally in O'Brasail for two days and saw out of it the Isles of Arran, Golam Head, Iross-beg Hill, and other places on the western continent which he was acquainted with. The manner of it he relates, that being in Iross-Ainhagh, in the south side of the Barony of Ballynahinshy, about nine leagues from Galway by sea in the month of April, A.D. 1668, going alone from one village to another in a melancholy humour upon some discontent of his wife's (!) he was encountered by two or three strangers and forcibly carried by a boat into O'Brasail, as such as were within told him -- and they could speak both English and Irish. He was ferried out hoodwinked in a boat, as he imagines, till he was left on the seaside by Galway, where he lay in a friend's house for some days after being very desperately ill, and knows not how he came to be there.
"In the western ocean, five or six leagues from the continent there is a sand bank about thirty fathoms deep in the sea. It is called in Irish, Imaire Bay, and in English, the Cod-fishing Bank. From this bank about twenty years ago, a boat was blown southwards by night; next day about noon the occupants spyed land so near them that they could see sheep within it, and yet durst not, for fear of illusions, touch shore, imagining it was O'Brasail, and they were two days coming back towards home.
"Some few generations ago, the crew of a fishing boat passing an island which they did not know, landed thereon to refresh themselves. They had no sooner landed than a man appeared and told them they had no business there as the island was enchanted. They therefore returned to the boat, but as they were going away the islanders gave one of them a book with directions not to look into it for seven years. He complied with the request and when he opened and read the book he was able to practice surgery and psychic with great success. This man's name was Lee, and the book remained as an heirloom with his descendants."
A high latitude mirage is caused by a temperature inversion created when the air immediately above the earth's surface is colder than air at higher elevations. Under these conditions, light rays are bent around the curvature of the earth. The stronger the inversion, the more bending. With a high degree of bending, the earth's surface looks like a saucer, and landscapes and ships normally out of sight below the horizon are raised into view on the saucer's rim. The effect can last for days and cover thousands of kilometers.
Writing in 1684 the Irish historian O'Flaherty recorded his belief in the enchanted island of Hy-Brasil as follows:
In the light of what we know today, the frequent appearance of this enchanted land to the west of Ireland could be explained by the phenomenon identified as a 'high latitude' mirage. This makes distant lands visible and may explain how Norse seamen discovered North America (although it already existed, of course!) around AD 1000. The high latitude, or Arctic, mirage differs from other mirages in that it reflects something that actually exists, in this case a real landscape that lies below, or beyond, the horizon. Such events have been recorded in the past as far south as England's south west coast and even an image of the coastal city of Bristol has been observed by viewers on the opposite side of the Atlantic.