This diagram shows the main avenues through which ancient sources report a connection between Zeno, the founder of Stoicism, and Socrates. When Zeno arrived in Athens, the culture was dominated by the personality of Socrates, who was executed 100 years before the Stoa was founded.
We’re told that as a young boy, Zeno read many books about Socrates, which his father, a merchant, brought back to Cyprus from his trips to Athens. We know little about Zeno’s first book, The Republic, except that it contained many criticisms of Plato’s Republic, which he’d clearly studied closely by the time he came to found the Stoa. One story tells us that Zeno was shipwrecked near Athens and stumbled across a copy of Xenophon’s Memorabilia of Socrates in a bookshop. He was so impressed that he asked the bookseller where he could meet a man like that and, by chance, Crates the Cynic was walking nearby and so Zeno was advised to become his follower.
For at least ten years before he went on to found his own school, Zeno studied a variety of philosophical approaches in Athens. He first became a follower of Crates the Cynic, about whom we’re told he later wrote a book recording his recollections. Crates had studied with Diogenes, who had reputedly studied with Antisthenes, the friend and follower of Socrates, placing Zeno in a kind of philosophical lineage descending from Socrates. Modern scholars believe it’s unlikely that Diogenes studied under Antisthenes. However, it’s possible that the ancient claim that Antisthenes somehow founded the Cynic tradition meant that Diogenes had studied and been greatly inspired by Antisthenes’ writings.
It’s less well-known that Zeno also studied with the heads of the Academy and Megarian school, which were also descended from Socrates. By studying the Megarian philosophy, Xenophon’s teaching, Platonism, and Cynicism, in detail, Zeno was exposed to a variety of different interpretations of Socrates’ original teaching. (It also seems that Zeno was influenced by Pythagoreanism, although all we know in this regard is that he wrote a book on the subject.) The early Stoics appear to have been less concerned with Aristotle, perhaps because he stood somewhat outside the Socratic tradition.