1. FOR the other apartments, that is, those intended to be used in Spring, Autumn, and Summer, as well as for atriums and peristyles, the ancients required realistic pictures of real things. A picture is, in fact, a representation of a thing which really exists or which can exist: for example, a man, a house, a ship, or anything else from whose definite and actual structure copies resembling it can be taken. Consequently the ancients who introduced polished finishings began by representing different kinds of marble slabs in different positions, and then cornices and blocks of yellow ochre arranged in various ways.