Cap. IX Sol: reprobation here means fixed decree not to give special efficacious grace — damnation from sin; denial of that grace from mere liberty of will
Recall again what we must keep repeating: by reprobation — which we hang from God's mere will, not from foresighted human demerits — we do not mean a peremptory decree to damn or eternally afflict some particular person, but a fixed decree not to impart that special efficacious grace, or calling according to purpose, without which God sees that person will remain in hardness, impenitence, and unbelief — and has decreed to permit that. God is most certain that from such passing-over the man so rejected will die in his sins, and most decided to damn him for those sins in which he will die. Yet it is plain: denial of that grace (where we locate reprobation properly) hangs on mere liberty of divine will, while that person's damnation arises from his own sin.
Latin
Hic in memoriam revocandum est, quod subinde cogimur repetere, nos, per reprobationem, quam ex mera Dei voluntate et non ex praevisis demeritis humanis suspendimus, intelligere, non peremptorium decretum damnandi, vel morte aeterna afficiendi singularem aliquam personam, sed fixum decretum non-impertiendi specialem illam et efficacem gratiam, sive vocationem secundum propositum, absque qua Deus videt hanc singularem personam in sua duritia, impoenitentia, et infidelitate permansuram, atque decrevit illud permittere. Est quidem Deo certissimum, ex tali praeteritione hominem sic rejectum in peccatis suis moriturum: Est etiam Deo decretissimum, eundem hominem damnare propter peccata illa in quibus morietur: interim tamen haud obscurum est, negationem talis gratiae (in qua reprobationem proprie sitam esse putamus) ex mera libertate Divinae voluntatis pendere, at damnationem talis personae ex peccato ejusdem oriri.