Charles and Clement could also control aspects of the prescribed liturgy and the music of
the Mass. It is clear from what we know of Charles’s personality that the ceremony–and not
least its music–was important to him. An oft-cited passage from Prudencio de Sandoval’s
biography of Charles V underscores the ruler’s interest in music:
“And he knew music, and felt it and liked it, for many times the friars, behind the door,
heard him leave his cell and go to the main altar, and they saw him beating time and singing
in harmony with those who sang in the choir...”