Shackleton's third man

In 1916 Ernest Shackleton, Tom Crean and Frank Worsley crossed the mountains of South Georgia on foot, and Shackleton later wrote that he often sensed a fourth man with the three of them. T. S. Eliot's use of the idea in The Waste Land gave the third man factor its name.

Australian Geographic says that in 1916 Ernest Shackleton set out with Tom Crean and Frank Worsley to cross South Georgia, an island in the South Atlantic near Antarctica, from its south coast to its north, hoping to reach one of the whaling stations Norwegians ran there. In South, his 1919 account of the 1914-1917 expedition, Shackleton wrote that he planned a route east to Stromness Bay, where whaling stations stood at Leith, Husvik and Stromness, and that the three men travelled light, leaving their sleeping-bags behind.

Shackleton described the crossing as a 36-hour march over South Georgia's glaciers and unnamed mountains. He wrote that it often felt to him as if there were four of them in a party of three. He kept this to himself, but afterwards Worsley told him he had felt a further person was with them on the march, and Crean admitted to the same. Shackleton added that words fall short for such things, but that leaving it out would leave the record of the journeys unfinished.

Australian Geographic says preachers used Shackleton's admission in sermons at the time, and it was also taken up at revivalist gatherings. T. S. Eliot's note to The Waste Land (1922) says a passage in the poem came from an account of an Antarctic expedition; he could not recall which, but thought it was one of Shackleton's. In that account, Eliot wrote, the exhausted explorers kept imagining that their party held one person more than they could count. Wikipedia places the passage at lines 359 to 365. In a 2009 NPR interview with John Geiger, titled The Third Man Factor, NPR notes that Eliot changed the fourth figure in Shackleton's account into a third, which is where the phenomenon's name comes from. Wikipedia adds that the name is used even when the experience comes to one person alone in danger.