So, who was Cicero trying to convert to his Platonic belief that eternal virtues are the highest good?
Was he succeeding in his goal? And is that the reason he kept at it, sensing that he was winning the game?
From an article regarding virtues this, on Plato vs. Aristotle.
QuoteEven though there were different Greek philosophers following the same moral view of virtue ethics, their interpretation was slightly different. For example, Plato and Aristotle treated virtues differently. Plato viewed virtue as an end to be sought for, where relations such as friendship could be a means. Aristotle, on the other hand, saw virtue as a means for happiness that safeguarded human relations.
Epicurus' stance seems to me to be built upon Aristotle's ideas, but yet adding in that "pleasure" is beneficial, and the ultimate end.
Philodemus wrote on virtues and vices:
QuotePhilodemus of Gadara wrote extensively about virtues and vices, with surviving fragments from works like On Vices and On Flattery detailing various vices such as arrogance, envy, greed, flattery, and anger, and contrasting them with their opposite virtues. He discussed how vices stem from false beliefs and habits while virtues arise from true beliefs and connection to Epicurean pleasures. Philodemus also explored the therapeutic methods for dealing with vices, such as the "therapy of vice," and the interconnectedness of vices and emotions within the soul.
Source: Google search, AI summary
Here is a scholarly article by Tsouna:
https://ancphil.lsa.umich.edu/-/downloads/osap/21-Tsouna.pdf
I find it interesting the differences in Cicero's "On End" compared to the "Tusculan D."