insertion of this kind, or the omission, intentionally or by oversight, of
a part of the original from the copy might, it will easily be seen, lead
one to conclude that there once existed a form of the story which as a
matter of fact never existed.

The version of the Táin which I have chosen as the basis for my translation
is the one found in the Book of Leinster (_Leabhar Laighneach_), a
voluminous vellum manuscript sometime called the Book of Glendalough and
now kept in the Library of Trinity College, Dublin, catalogue number
H. 2. 18. Only a part of the original book remains. It dates from about the
year 1150. This date is established by two entries in the manuscript
itself: "Aed son of Crimthann (Hugh macGriffin) hath written this book and
out of many books hath he compiled it" (facsimilé, at the bottom of page
313). Who this Aed was will be clear from the other entry. It appears that
he had lent the manuscript while still unfinished to Finn macGorman, who
was Bishop of Kildare from 1148 and died in the year 1160, and who on
returning the book wrote in it the following laudatory note in Irish to
Aed: "(Life) and health from Finn, the Bishop of Kildare, to Aed son of
Crimthann, tutor of the chief king (i.e. of King Dermod macMurrogh, the
infamous prince who half a century later invited Strongbow and the Normans
to come over from Wales to Ireland) of Mug Nuadat's Half (i.e. of Leinster
and Munster), and successor of Colum son of Crimthann (this Colum was abbot
of Tir da ghlass the modern Terryglas on the shore of Lough Derg, in the
County Tipperary--and died in the year 548), and chief historian of
Leinster in respect of wisdom and intelligence, and cultivation of books,
science and learning. And let the conclusion of this little tale (i.e. the
story of Ailill Aulom son of Mug Nuadat, the beginning of which was
contained in the book which Finn returns) be written for me accurately by
thee, O cunning Aed, thou man of the sparkling intellect. May it be long
before we are without thee. My desire is that thou shouldst always be with