I realize I actually read a bit ahead yesterday. Mea culpa.
“There await us, if ever we escape from these low dregs to that sublime and lofty height, peace of mind and, when all error has been driven out, perfect liberty. You ask what this freedom is? It means not fearing either men or gods; it means not craving wickedness or excess; it means possessing supreme power over oneself And it is a priceless good to be master of oneself.”
I set about trying look more into the classification of the προκόπτωντες. I wasn’t quite able to hunt down the reference in Epictetus, other than the general fool/sage distinction. Of course, what the vicissitudes of Fate have given us of Chrysippus is scanty at best.
I did find this work by Geert Roskam, “On the Path to Virtue: The Stoic Doctrine of Moral Progress and Its Reception in (Middle-) Platonism.” Maybe I’ll save my pennies and see if I can secure a copy.