This psalter was made in Ireland (Armagh?), probably in the late 12th century to judge from the style of the script. The scribe signed his name on one of its pages: 'Cormacus wrote this psalter: pray for him'. Its decoration shares some features of manuscripts from Armagh, but it combines stylistic elements seen in 8th- and 9th-century illumination (in masterpieces such as the Book of Kells) with current styles. Containing canticles or verse passages from the Bible, such as Deut. 32:1-43, as well as the Book of Psalms, it was used as a prayerbook or hymnal in church services. The first letter of Psalm 51 (52) has been expanded to the size of the page. Its form becomes the body of a dog, in brilliant colours, the purple burnished to give a striking polished surface. It is set within a red field embellished with cord-like yellow interlace, the ends of which bear animal and human heads. This Psalm receives special decorative attention to mark one of three traditional Irish divisions of the Psalter, at Psalms 1, 51, and 101. The top of the initial is cropped: at some point in its history, the manuscript was trimmed, probably when it was rebound.