In 1974 the American Roman Catholic theologian Avery Dulles published an instructive and successful book called Models of the Church, the heart of which considers the church as institution, as mystical communion, as sacrament, as herald, and as servant. It includes a chapter on ‘The church and revelation’, later expanded as a further book called Models of Revelation; but at that point difficulties surely arise. The notion of models as Dulles applies it to the church enables him to take account of the fact that the church is a concrete objective reality, yet one whose nature is complex and difficult to encapsulate. Images which emerge from Bible and tradition, such as the ones Dulles studies, can be applied with a degree of analytical rigour to the church, with illuminating results. Some of these images may be better described as metaphors. They take actual entities such as a herald and use them to cast light on the nature of the church by analogy; they are less systematically developed than models and are more consistently capable of operating at other levels as well as the intellectual (though in theology, at least, models also commonly carry strong emotional associations and thus may profoundly influence attitudes as well as shape conceptual thinking). Some of the images are models in a stricter meaning of the word; they do not in themselves exist in the same sense as the church does, but as constructs they enable us to grasp aspects of the significance of the church conceptually.