The Psalters Themselves
During the pre-reformation days, it was not customary for lay members of a church's congregation to communally sing hymns. Singing was done by the priests and other clergy; communal singing of Gregorian chant was the function of professional choirs, or among communities of monks and nuns. John Calvin, inspired by Erasmus's comments, desired singable versions of the Psalms and other Christian texts for the communal use of the Reformed churches.
Read more about this topic: Split-leaf Psalter