Where it comes from
Oil massage is the oldest tool in the drawer, the Greeks oiled and worked the body at the baths, and the strokes taught in every European school since Ling's Stockholm curriculum are built for exactly this medium. What the erotic version adds is not a new stroke but an old candour: the nineteenth-century spa towns kept it discreetly on the menu, Amsterdam put a lamp over it and a price on it, and the format has never needed improving since, good classical work, allowed to end up somewhere warmer.