The Third Man Factor by Canadian author John Geiger, who claims that it’s not just experienced by explorers but has been reported by many other people, such as those rushing out of the Twin Towers on 9/11. Geiger points out that it’s a sort of positive hallucination that actively gives us support. It’s as if our brain has worked out that in times of extreme peril we need someone beside us, so we very literally conjure up an imaginary friend to help us survive, or rather comfortingly, see us through to the end.
