The Christian sacrament is at once cause and sign. Each sacrament is a cause which signifies the kind of grace it produces and a sign which causes what it signifies. In the sacrament we have a perfect coincidence of sign and instrument, for in performing the signifying action we are also constructing an instrument used by God to confer grace. Now it is obvious that the causing of grace is something much more mysterious and much more important than its signification, and in the face of a Protestant criticism which denied all efficiency to the sacraments and saw them simply as symbols or memorials of Christ's life, it is not suprising that Catholic apologetics should have emphasized this causal character of the sacraments. The Christian sacrament is a genuine cause of grace, operating not only dispositively or ‘morally’, but directly causing what it signifies.