Early medieval Christians inherited from pagan and Jewish traditions a firm understanding of Hell as a place where impious souls suffered after death, but they wrestled with the notion of where it was located. During the “dark ages” of European history (500–750 CE), monastic authors depicted the location and features of Hell in stories about visions of the afterlife. In these stories, the souls of ailing individuals made journeys to the otherworld to witness the horrors of Hell and the pleasures of Heaven, before returning to tell their tales to the living to encourage the cultivation of virtue and the avoidance of sin. The depiction of Hell in these stories was complicated by the fact that Christian thinkers like Pope Gregory the Great (c. 540–604 CE) and the Venerable Bede (672/73–735 CE) were also formulating the earliest ideas about Purgatory, a place between Heaven and Hell where the souls of the dead suffered in fire to purge them of their sins before they entered Heaven.

The introduction of the concept of Purgatory had a strong influence on depictions of Hell in the early Middle Ages. Whereas souls in Purgatory had every hope of entering Heaven once their painful cleansing by fire was complete, the wicked bound for Hell would never escape the punishments awaiting them there. Their suffering would last forever. As a result, early medieval visions of the afterlife written by Gregory the Great and the Venerable Bede focused on the transient torments of sinful souls preparing for entry into Heaven and brought the reader only to the lip of Hell’s abyss without venturing any further, perhaps because the horrors awaiting unrepentant sinners were not as useful for encouraging the moral reform of individuals as the pains of Purgatory or perhaps because they were simply too terrible to contemplate. In contrast, the story of Saint Brendan’s encounter with Judas Iscariot on the trackless ocean blended elements of pre-Christian Irish mythology, particularly the immram tradition, in which heroes traveled by sea to the otherworld, and the ancient Homeric tradition, which located the entrance to Hades on a dark and distant shore.