In last month's article ‘Sacrament and Symbol’ we say something of the nature of the sacramental sign and its relationship to the human creature for whom it was instituted. But the sign exists for the sake of the thing signified and its most important function (though not its only function) is to lead us to a knowledge of this thing signified. In this article, therefore, I propose to give a short account of what St Thomas understood by res sacra, the sacred reality lying behind the sign.

For this sacred reality is the thing signified. ‘A sacrament, says St Augustine, ‘is the sign of a sacred reality’; and St Thomas adds, ‘in so far as it is making men holy’. The Augustinian definition is too wide; as wide, in fact, as it possibly can be for it includes the whole of creation.