Once again, these notes take as their point of departure a reading and summary of Tad Brennan's The Stoic Life. It would be pointless to cite every single fact (most of them are basic, dictionary-type facts anyway, so there is no great need), but occasional page number references and quotations are from Brennan.
We call that philosophy "Socratic," but it is mostly found in Plato. Simply put, there is a hypothesis that Plato's writings can be divided. Some (usually called the "early" dialogues) are faithful reporting of Socrates' ideas.

But other Platonic dialogues go far beyond the exclusively virtue-oriented philosophy which is called "Socratic" above.

These "middle" and "late" Platonic dialogues are also part of the environment of Stoicism's early days.
Aristotle was Plato's student, and a towering intellect, but he had no irrefutable impact on Stoics, strangely enough.
Nonetheless, Brennan claims, the Stoics did adopt one feature of Aristotelian ethics. That feature is the idea that everything we do, we do for the sake of some further thing, and that thing is done for a further thing, until we come to a thing which we do purely for its own sake. That final thing is called the end or the final end, the summum bonum (greatest good). Each school tried to say what its final end was, and how achieving it involved Virtue and Eudaimonia.

There were two Hellenistic schools of philosophy which rivaled the Stoics: Sceptics and Epicureans.
SOME SIMILARITIES AND DIFFERENCES BETWEEN MODERN AND ANCIENT ETHICAL THEORIZING