Das Chorbuch Aus Leiden 3

The survival of the Leiden Choirbooks from the iconoclastic fury
in 1566 seems to indicate that the manuscripts were carefully kept
somewhere under lock and key in the church. Today, these choirbooks
provide unique and extremely valuable proof of the rich musical life
of 16th-century Holland. Even though musical practice flourished
greatly in Dutch churches in 16th century, little evidence of this has
survived in Dutch archives and libraries. Of the countless music
manuscripts that were used by singers of the liturgical hours as well as
others, only a fraction of these have survived the ravages of time.