The manuscript (CLLA 352) came from the Abbey of Silos. After the monastery’s suppression in 1835 the library was kept together for a time by the last abbot, Dom Rodrigo Echevarria, afterwards Bishop of Segovia, but in 1878 the library was sold in Paris and divided between the British Museum Library and the Bibliotheque Nationale. Some books, of course, escaped, and were restored to the French Benedictines who repopulated Silos. This MS most probably dates from the eleventh century. Gilson’s work includes the sections for the Psalter, the canticles, hymns, and canonical hours, in a diplomatic edition with a minimum of editorial intervention.