No single interpretation exhausts the meaning of a complex image. Several interpretations enrich the understanding of a single image. The interpretation of an image is determined by formal and content aspects. The formal ones influence the mental ones. First of all interpretation depends on the approach.
Interpretations are answers to questions that people have, it is what one wants to see in an image.
There is a modern, semiotic and a traditional, iconological, interpretation. There are all kinds of variations and combinations possible. The division in lower and higher reading which Dante made in 1302, is comparable to that by Panofsky in 1962. Indeed the handbooks by Ripa and Van Mander were used in art schools until the beginning of this century. The different way of handling the formal elements asked for a new, technique based approach which was given by Wolfflin in 1915.