Understand, 'in the present order of providence,' not in that possible, but unrealised order of mere nature, in which God never intends to raise His rational creature to grace and beatific vision. Cf. B. III, Chap. L, with notes. In the order of mere nature, what Catholic divines now understand by 'original sin' would have been an impossibility. Of this difficult doctrine of original sin, the best English exposition is in the Essay on the Immaculate Conception in the late Father Harper's Peace through the Truth, First Series.
Of God and His Creatures: 4.50