I want to plunge into my subject by adopting that practice well known to our medieval predecessors, namely to use an exemplum, because at once it transports us into the heart of the problem to be addressed. The event is recounted by Orderic Vitalis in Book Six of his Ecclesiastical History, and describes the practice of a Norman priest called Gerold who served in the household of the great earl of Chester Hugh of Avranches (1071–1101). Gerold was, apparently, a devoted priest who regularly said the offices for the day and offered Mass, but beyond this he wanted die men of the earl's household to live a better life. That desire he discharged by telling them about how some of their forebears had lived:
To great lords, simple knights, and noble boys alike he gave salutary counsel and he made a great collection of tales of the combats of holy knights, drawn from the Old Testament and more recent records of Christian achievements, for them to imitate. He told them vivid stories of the conflicts of Demetrius and George, of Theodore and Sebastian, of the Theban Legion and Maurice its leader, and of Eustace, supreme commander of the army and his companions, who won die crown of martyrdom in heaven. He also told diem of the holy champion, William, who after long service in war renounced die world and fought gloriously for die Lord under die monastic rule. And many profited from his exhortations, for he brought them from the wide ocean of the world to die safe haven of life under the Rule.