Augustine, Disputation against Fortunatus 17
Augustine responds to Fortunatus who has just quoted Ephesians 2.1-18.
ergo nunc quaero abs te, secundum eam lectionem quae lecta est, quomodo habeamus peccata, si natura contraria nos cogit facere quod facimus? qui enim cogitur necessitate aliquid facere, non peccat. qui autem peccat, libero arbitrio peccat.
Therefore I ask of you, according to that passage which has been read, how are we to have sins if contrary nature forces us to do what we do? For the man who is forced to do something by necessity does not sin. But the man who does sin sins by free will.