A towel, The Hitchhiker's Guide to the Galaxy says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the
cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapors; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the
slow heavy River
Moth; wet it for use in hand-to-hand-combat; wrap it round your
head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter
Beast of Traal (such a mind-boggingly stupid animal, it assumes that if you can't see it, it can't see you); you can wave your towel in emergencies as a distress signal, and of course
dry yourself off with it if it still seems to be clean enough.
Any man who can hitch the length and breadth of the
galaxy,
rough it, slum it, struggle against
terrible odds, win through, and still knows where his towel is is clearly a man to be reckoned with.