The Book of Psalms begins with the words Beatus vir (Happy is the man). To mark the beginning of the text of the psalms in manuscripts, an entire page is often devoted to the initial B from this verse, almost always richly illuminated. In this psalter, King David, who was believed to have written the psalms, sits in the lower lobe of the initial B. The artist presents David in his role as composer of the psalms, aided by two musicians, one with a harp, the other with a lyre. David sits enthroned in the center, aligned with the figure of Jesus blessing above. This typological arrangement presents David as an Old Testament prefiguration of Christ.
The artist created an elaborate design to introduce the text of the psalms. Blue bands decorated with silver and held together by a biting animal head and gold clasps form the basic shape of the letter, which is entwined in curling tendrils of green, red, and purple. Animals and human forms inhabit these vine scrolls. The brilliant deep colors and the figures' sumptuous dress add to the majesty of the image.