Pictures are the idea in visual or pictorial form; and the idea has to be legible, both in the individual picture and in the collective context - which presupposes, of course, that words are used to convey information about the idea and the context. However, none of this means that pictures function as illustrations of an idea: ultimately, they are the idea. Nor is the verbal formulation of the idea a translation of the visual: it simply bears a certain resemblance to the meaning of the idea. It is an interpretation, literally a reflection.