Researchers in Pennsylvania have discovered what they believe are among the earliest written music notes in Western history. These notes were found on a ninth-century manuscript that was “hidden in plain sight” for many years in a private collection. The notations, resembling shorthand outlines, appear above the word “alleluia” on the manuscript, a vellum leaf from a Latin sacramentary. This Catholic liturgical book was used during mass in Western Europe from the mid- to late 800s.