/summa/TP/TPIII/TP_Q61:
We must now consider the necessity of the sacraments; concerning which there are four points of inquiry:
(1) Whether sacraments are necessary for man's salvation?
(2) Whether they were necessary in the state that preceded sin?
(3) Whether they were necessary in the state after sin and before Christ?
(4) Whether they were necessary after Christ's coming?