Written in Latin. The Cathach is the oldest extant Irish manuscript of the Psalter and the earliest example of Irish writing. It contains a Vulgate version of Psalms XXX (10) to CV (13) with an interpretative rubric or heading before each psalm. It is traditionally ascribed to St. Columba as the copy, made at night in haste by a miraculous light, of a Psalter lent to Columba by St. Finnian. A dispute arose about the ownership of the copy and King Diarmait Mac Cerbhaill gave the judgement “To every cow belongs her calf, therefore to every book belongs its copy”. The arbitration failed and the Psalter of St. Columba passed into the hands of the O’Donnells after the battle of Cul Dremhne in A.D. 561. St. Columba went to Iona in A.D. 563. It is possible to date the manuscript to the late 6th or early 7th century from the script, but modern historical scholarship has cast doubts on the authorship by St. Columba as well as on the dating.
 
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