The Sacramentarium Leonianum (also known as the Verona Sacramentary) is the oldest surviving Western Christian liturgical book. It is not a narrative text, but rather a practical guidebook containing texts for prayers and the manner of celebration of the Eucharist and other sacraments used by priests (presbyters) during liturgical celebrations. The following are the main points about the Sacramentarium Leonianum. It is a sacramentary, that is, an ancient liturgical book that includes only the parts said by the bishop or principal priest during Mass and other sacramental ceremonies, such as the prayers (collections, offertory prayers, prefaces, canons, etc.). It contains a collection of prayers and rubrics (instructions on the manner of celebration) for various liturgical celebrations, including daily celebrations of the Eucharist, ecclesiastical feasts, ordinations, and the celebration of other sacraments. It is thought to date from around the 6th or 7th century, although the texts may be older. The most complete original manuscript is found in Verona, Italy, and is often referred to as the Verona Sacramentarium. Briefly, the Sacramentarium Leonianum is an ancient compendium of prayers and liturgical guide for priests, serving as an important historical record of how the Mass and sacraments were celebrated in the early Western Church.