Hildegard of Bingen (hĭlˈdəgärthˌ, bĭngˈən) [key], 1098–1179, German nun, mystic, composer, writer, and cultural figure, known as the Sibyl of the Rhine. An aristocrat educated in a Benedictine convent, she began experiencing mystical visions as a child. Entering religious life c.1116, she became an abbess in 1136 and founded her own convent at Rupertsberg near Bingen c.1147. Mystical and worldly, she was deeply immersed in religious life yet also involved in political and cultural affairs, maintaining a lively and wide-ranging correspondence. Her theological magnum opus, Scivias (c.1151), contains 26 visions. Today she is best known for her richly lyrical liturgical poetry set to her own innovative monophonic chants, composed mainly in the 1140s and collected in the 1150s. She also wrote a medical encyclopedia, scientific treatises, works of natural history, lives of saints, and other works. Widely proclaimed a saint, she has not been canonized; nonetheless, her feast day is celebrated on Sept. 17.