Chapter 20 — Part II: The Sacraments — Extreme Unction
Section 12. It should not excite surprise that, while the form of each of the other Sacraments either absolutely signifies what it expresses, such as I baptise thee, or I Sign thee with the sign of the cross, or is pronounced, as it were, by way of command, as in administering Holy Orders, Receive power, the form of Extreme Unction alone is expressed by way of prayer. Wisely has it been so appointed. For since this Sacrament is administered not only for the spiritual grace which it bestows, but also for the recovery of health, which, however, is not always obtained, therefore use a deprecative form, in order to implore of God's mercy what the virtue of the Sacrament does not always and uniformly effect.