The motive that prompts the decoration, at whatever cost, of interiors in colder climes suggested to the Oriental the embellishment of his house-top. The parapet ordered by Moses became a potter's triumph;above that, later, arose towers, plain and fantastic;still later, kings and princes crowned their roofs with summer-houses of marble and gold. When the Babylonian hung gardens in the air, extravagance could push the idea no further.