Why is most of the surviving music from the Middle Ages centered on religious themes?

The focus of surviving music from the Middle Ages on religious themes is primarily due to the patronage of the church. During this period, the Catholic Church was a dominant influence in society and culture, and it played a key role in the creation, preservation, and transmission of music. The church not only commissioned works to enhance liturgical services but also maintained vast resources for the training of musicians and the development of musical notation. This patronage allowed for the composition of a wealth of sacred music, much of which has survived to this day, whereas secular music often lacked similar support and resources.

In contrast, while certain secular music genres may have been enjoyed by the nobility or the general populace, they did not receive the same level of preservation or documentation. Religious melodies also often had the advantage of being more systematically notated, but it was primarily the church's influence and commitment to sacred music that ensured these works were created and maintained throughout the ages.