The Voyage of Maeldun
12th century, Old Irish. Lebor na hUidre (Book of the Dun Cow), Royal Irish Academy, Dublin.
A shepherd stands between these flocks and when he takes a white sheep over to the other side of the wall, it turns black, and when he brings a black sheep across the wall it turns white.
From the Book of the Dun Cow, written in Old Irish in about 1104 and now lying at the Royal Irish Academy in Dublin: Maeldun and his crew have been blown into an enchanted sea. It is a sea in many ways similar to the one in which Odysseus sailed, perhaps hinting at the true antiquity of this tale. There are islands on which giants live, islands of luscious fruit and laughing folk, islands of animals, islands where a goddess lives who wishes, like Circe, to invite them into her abode.
Near one particular island, Maeldun and his crew can see, from where they are lying offshore, a flock of black sheep and a flock of white sheep separated by a high wall. A giant shepherd stands between these flocks and when he takes a white sheep over to the other side of the wall, it turns black, and when he brings a black sheep across the wall it turns white. Maeldun cuts a white stick from a bundle on the ship and throws it onto the side of the island where the black sheep are all grazing and it turns black before it lands.
They sail away in some anxiety.