Sulgenus Sapiens, Sulien the Wise of Llanbadarn Fawr in Ceredigion, was twice bishop of St David's. Quotations and allusions imply that Rhygyfarch and Ieuan had studied, first in the classical and Late Latin tradition, Vergil, Ovid, Lucan, Juvencus, Prudentius, Martianus Capella, Caelius Sedulius, Boethius, and possibly Statius, Horace and Juvenal. Second, the prose Lives imply that Rhygyfarch and Ieuan had studied the works of the primary Cambro-Latin author, Gildas: De excidio Brittanniae, Epistolae, and Penitential. In the third place, both brothers knew the earliest Armorico-Latin hagiographic text, the eighth-century Vita Sancti Samsonis. Rhygyfarch borrowed from the Life of Gregory and the Life of Samson stories about the golden-beaked dove, bringing them into play earlier in the Life of David and closer to his person than in the sources. Ieuan's poem in praise of his father records extended periods during which Sulien had studied in Ireland and in Scotland.