The divine songs and constructed language of Hildegard von Bingen.
Hildegard von Bingen was not only a composer and mystic, but also a pioneering linguist. She created Lingua Ignota (Latin for "unknown language"), which is widely considered to be one of the earliest known constructed languages (conlangs) in human history.
Consisting of a 23-letter alphabet (the litterae ignotae) and a glossary of over 1,000 invented words, Lingua Ignota was used to write ecstatic hymns and express mystical concepts that Hildegard felt could not be fully captured by traditional human language alone.
Hildegard's musical compositions pushed the boundaries of medieval liturgical music with their soaring, monophonic chants and deeply emotional texts.