Guests at the Paris Hermès show didn’t just see the collection, they smelled it first. The Garde Républicaine — the grand barracks of Paris’ mounted police — had been transformed on Saturday into a forest floor, carpeted in thick, damp moss that filled the air with the heady scent of humus. In a Paris Fashion Week that still has Chanel and Louis Vuitton to come, Hermès made a case that luxury at its most persuasive doesn’t shout. It simply changes the air in the room. Models emerged from luminous circular openings in the walls, like figures stepping through a full moon, and walked a raised, winding catwalk above the vegetation.