Cap. VI Arg. 10: comparative election and rejection — an inscrutable abyss
In comparative election and rejection of men there is an inscrutable abyss — a secret no human curiosity may pry into. Brought back to the sums of human reason, it would look like injustice: of two wholly equal, one is destined to life by God's gracious good pleasure, the other left.
Latin
In comparativa electione et rejectione hominum est abyssus quaedam inscrutabilis, et arcanum nulla humana curiositate pulsandum. Nam si ad rationis humanae calculos revocaretur, injustitiae speciem prae se ferret, quod ex duobus prorsus aequalibus unus gratioso beneplacito Dei ad vitam destinatur, alter relinquitur.