May we not however observe that as in the natural order of things God has provided, in the acquired skill of physicians and surgeons, certain ordinary means for healing the sick and even giving sight to the blind, so in the supernatural order He has provided an ordinary means for the justification of the sinner in the Sacraments of Baptism and Penance? Miracles are exceptional, but the forgiveness of sins is part of the Church's daily ministry; and the gratia praeveniens, necessary to bring the sinner to avail himself of this ministry, has to be presupposed as part of the institution. The fuller and fuller recognition of this consoling truth is a typical instance of the 'development' of the mind of the Church.
On the texts from Romans quoted here cf. Notes on St Paul pp. 393-397.
Of God and His Creatures: 3.162