Noun
The hymns or sacred lyrics composed by authors of a particular country or period; as, the hymnology of the eighteenth century; also, the collective body of hymns used by any particular church or religious body; as, the Anglican hymnology.
A knowledge of hymns; a treatise on hymns.
Source: Webster's dictionaryAccording to the Dictionary of American Hymnology "Amazing Grace" is John Newton 's spiritual autobiography in verse. Source: Internet