I'd be happy to tell you about St. Yared of Ethiopia.
St. Yared (also spelled "Yarid" or "Yareda") was an Ethiopian Orthodox Christian monk and musician who is believed to have lived between the 6th and 7th centuries. He is best known for his contributions to Ethiopian liturgical music, particularly the creation of the Zema, a form of chanting that is an integral part of Ethiopian Orthodox Christian worship.
According to tradition, St. Yared was born in the region of Aksum in northern Ethiopia. He was an orphan who was raised by his uncle, a priest who taught him the scriptures and introduced him to the church's musical traditions. St. Yared was said to have been particularly talented in music, and he devoted himself to composing hymns and chants for use in the church.
One of St. Yared's most significant contributions to Ethiopian music was the development of a system of musical notation called "neume," which allowed for the written preservation and transmission of the Zema chants. This system is still used in Ethiopian Orthodox Christian liturgy today.
St. Yared is also credited with organizing the church's musical repertoire into a structured system, categorizing the chants according to their purpose and style. He is said to have composed more than 800 hymns and chants, many of which are still sung in the Ethiopian Orthodox Church today.
St. Yared is venerated as a saint in the Ethiopian Orthodox Church, and his feast day is celebrated on November 11th. His contributions to Ethiopian music and the church's liturgy have had a lasting impact, and he is revered as one of Ethiopia's greatest cultural and religious figures.
St. Yared is primarily known for his contributions to Ethiopian liturgical music rather than for any books that he authored. However, there are a number of books and manuscripts that contain collections of his hymns and chants, as well as writings about his life and musical contributions.
One of the most significant of these is the "Deggua Ts'om," a book of hymns and chants that is considered one of the foundational texts of Ethiopian Orthodox Church music. The book is attributed to St. Yared and contains over 300 hymns and chants that are still sung in Ethiopian Orthodox Church worship today.
Other books and manuscripts that contain St. Yared's hymns and chants include the "Geez Mezmur," a collection of Ethiopian Orthodox hymns and prayers, and the "Sarneghedd," a collection of liturgical chants used in Ethiopian Orthodox worship.
While St. Yared is not known to have authored any books or treatises on music theory or composition, his contributions to Ethiopian liturgical music have had a profound influence on the development of Ethiopian Orthodox Church music and continue to be celebrated and studied today.