Travellers or ghosts?
"Travel can induce such a distant and nameless feeling of strangeness and disconnection in me that I feel insubstantial, like a puff of smoke, merely a ghost, a creepy revenant from the underworld, unobserved and watchful among real people, wandering, listening while remaining unseen. Being invisible - the usual condition of the older traveller - is much more useful than being obvious. You see more, you are not interrupted, you are ignored." (Ghost Train to the Eastern Star, Paul Theroux)