Adomnán's most important work, and the one for which he is best known, is the Vita Columbae (i.e. "Life of Columba"), a hagiography of Iona's founder, Saint Columba, probably written between 697 and 700. The format borrows to some extent from Sulpicius Severus' Life of Saint Martin of Tours. Adamnan adapted traditional forms of Christian biography to group stories about Columba thematically rather than chronologically, and present Columba as comparable to a hero in Celtic mythology. Wetherill suggests that one of the motivations for writing the Vita was to offer Columba as a model for the monks, and thereby improve Adomnan's standing as abbot. The biography is by far the most important surviving work written in early medieval Scotland, and is a vital source for our knowledge of the Picts, as well as a great insight into the life of Iona and the early medieval Gaelic monk.