Complex sentence: Most of the hymns were taken out of other hymnals, among which some from the Hymns Ancient and Modern-his friend John Stainer was asked to help revise the Hymns Ancient and Modern.
Split into simpler sentences: Most of the hymns were taken out of other hymnals. Some came from the Hymns Ancient and Modern; his friend John Stainer was asked to help revise the Hymns Ancient and Modern.