Although agreeing with Zeno that Virtue was the supreme good, he rejected the idea that morally indifferent things such as health and wealth could be ranked according to whether they are naturally preferred.
[7] meaning that Arcesilaus presented himself as a Platonist, the substance of what he taught was the dialectics of Diodorus, but his actual philosophy was that of Pyrrhonism.
[10] Zeno divided philosophy into three parts: Logic (which was a very wide subject including rhetoric, grammar, and the theories of perception and thought); Physics (including not just science, but the divine nature of the universe as well); and Ethics, the end goal of which was to achieve happiness through the right way of living according to Nature.
"[16] For Aristo, Ethics was the only true branch of philosophy, but he also limited this category, removing its practical side: advice concerning individual actions was largely useless: He holds that it does not sink into the mind, having in it nothing but old wives' precepts, and that the greatest benefit is derived from the actual dogmas of philosophy and from the definition of the Supreme Good.
While agreeing with Zeno that Virtue was the supreme good, he totally rejected the idea that external advantages (health, wealth, etc.
For that the wise man resembles a good actor; who, whether he is filling the part of Agamemnon or Thersites, will perform them both equally well.
[22]The problem remains of how one can achieve a virtuous state if one can not make rational choices between which things in life are preferred and dispreferred and has only an abstract goal of perfect virtue.
[25]Aristo came to be regarded as a marginal figure in the history of Stoicism, but in his day, he was an important philosopher whose lectures drew large crowds.
[26] Eratosthenes, who lived in Athens as a young man, claimed that Aristo and Arcesilaus were the two most important philosophers of his age.
Chrysippus, (head of the Stoic school from c. 232 to c. 206 BC), systemized Stoicism along the lines set down by Zeno, and in doing so, was forced to repeatedly attack Aristo:
To maintain that the only Good is Moral Worth is to do away with the care of one's health, the management of one's estate, participation in politics, the conduct of affairs, the duties of life; nay, to abandon that Moral Worth itself, which according to you is the be-all and the end-all of existence; objections that were urged most earnestly against Aristo by Chrysippus.