We'll pick up this week at Section 12 of Part 5 of Tusculan Disputations. Here Cicero's student points out that Cicero has been contradicting himself in his own books as to the significance of the different positions on whether virtue alone is sufficient for happiness.
Cicero - Tusculan Disputations - EpicureanFriends Handbook
The heart of this argument is going to reveal how the line of non-Epicurean Greeks including Pythagorus/Socrates/Plato and the others listed here insist on finding the good only through their divinely-ordained reasoning of the mind:
QuoteBut the human mind, being derived from the divine reason, can be compared with nothing but with the Deity itself, if I may be allowed the expression. This, then, if it is improved, and when its perception is so preserved as not to be blinded by errors, becomes a perfect understanding, that is to say, absolute reason, which is the very same as virtue. And if everything is happy which wants nothing, and is complete and perfect in its kind, and that is the peculiar lot of virtue; certainly all who are possessed of virtue are happy. And in this I agree with Brutus, and also with Aristotle, Xenocrates, Speusippus, Polemon.