The third man factor or third man syndrome refers to the reported situations where an unseen presence, such as a spirit, provides comfort or support during traumatic experiences. History Sir Ernest Shackleton, in his 1919 book South, described his belief that an incorporeal companion joined him and his men during the final leg of his 1914–1917 Antarctic expedition, which became stranded in pack ice for more than two years and endured immense hardships in the attempt to reach safety. Shackleton wrote, "during that long and racking march of thirty-six hours over the unnamed mountains and glaciers of South Georgia, it seemed to me often that we were four, not three". His admission resulted in other survivors of extreme hardship coming forward and sharing similar experiences. Lines 359 through 365 of T. S. Eliot's 1922 modernist poem The Waste Land were inspired by Shackleton...