Chorale book
A collection of hymn tunes, usually with bass, for organists to accompany congregational singing.
What it means
A chorale book is a collection of hymn tunes for practical use in worship, usually set in four parts or given as melody with figured bass. It served organists as a reference so they could accompany congregational singing consistently and correctly without memorizing or harmonizing every tune themselves.
Musical use
Chorale books emerged mainly from the 18th century onward in Protestant church life and were published regionally or by individual state churches, often with prefaces on the intended tempo and ornamentation. They also settled which version of a tune was authoritative in a given area, since chorale melodies had changed over time and place.
A chorale book should be distinguished from a hymnal, which contains only the texts and usually just the melody line for the congregation, not the full, multi-part organ setting.
Performance practice
When accompanying congregational singing from a chorale book, set your tempo by the breathing of the singing congregation, not by the printed texture alone — older chorale books often assumed a slower pace of singing than the notation suggests.