To Florus 2.174
For after saying, ‘It passed into all human beings,’ he immediately added, ‘in whom all sinned’ (Romans 5:12). This phrase, ‘in whom all sinned,’ indicates nothing other than ‘because all sinned,’ in accordance with David’s words: ‘In what does a young man correct his way?’ (Psalm 119:9;) That is, ‘How does he correct his way?’ ‘By keeping your words’ (Psalm 119:9; LXX/Vulgate 118:9). He is thus said to be corrected ‘in’ that through which he is corrected. Likewise, the apostle said death passed on ‘in’ the fact that all sinned by their own will. The phrase ‘in whom’ should not be taken to indicate either Adam or sin; it should be understood as expressing the fact that all sinned.
Latin
Postquam enim dixerat: In omnes homines pertransiit, subdidit statim: in quo omnes peccaverunt; hoc: in quo omnes peccaverunt, nihil aliud indicat quam: Quia omnes peccaverunt secundum illud Davidicum: In quo corrigit adulescentior viam suam? Id est: Quomodo corrigit viam suam? In custodiendo sermones tuos [n276] . Io eo ergo corrigi dicitur, per quod et corrigitur. Ita et Apostolus in eo dixit pertransisse mortem, in quo omnes propria voluntate peccaverunt, non ut hoc: in quo aut Adam aut peccatum videatur ostendere, sed in quo omnes peccantes intellegatur exprimere.