Origin and designation. The standard designation in the sources is Ἀπολλώνιος ὁ Χαλκηδόνιος ("Apollonius of Chalcedon"), from Χαλκηδών — the city in Bithynia on the Asiatic side of the Bosporus, opposite Byzantium. Dio Cassius (71.35) calls him "Νικομηδεύς" ("of Nicomedia," from Nicomedia, the chief city of the same province). The modern consensus (Birley, Hadot, Hard, Farquharson): this is one and the same man; the confusion of the variants goes back to the proximity of the two cities and to a common Asiatic-Bithynian tradition; "of Nicomedia" perhaps refers to the place of his teaching, "of Chalcedon" to the place of birth.

Career before Rome. Before the summons to Rome, Apollonius perhaps taught at Athens (the sources do not say so directly; per SHA Pius 10.4 he was summoned from Chalcis) — which in the second century meant belonging to one of the principal successor schools of the Stoa (the old Stoa of Zeno and Chrysippus no longer existed as an institutional school, but Athens remained the centre of philosophical instruction, especially after Hadrian's reforms, which established state-funded chairs of philosophy at Athens). On indirect evidence (Galen, Lucian) Apollonius was among the most financially successful philosophical teachers of his generation, which in second-century Athens meant paying pupils and a position of some influence.

The summons to Rome. Around 138–140 (shortly after the accession of Antoninus Pius and the adoption of Marcus) Antoninus Pius specifically summoned Apollonius to Rome (per SHA Pius 10.4, from Chalcis) to take charge of the education of the adopted heir. This is a characteristic Antonine practice: Hellenistic-philosophical teachers of high rank were imported to Rome for the instruction of the heirs and of the senatorial elite. Apollonius arrived in Rome, it seems, accompanied by a group of disciples (Lucian's "Argonauts" — see below).

The anecdote of the refusal to appear at the palace. SHA Pius 10.4 reports: when Apollonius arrived in Rome and was summoned to the palace to teach Marcus, he answered that "it is not for the teacher to go to the pupil, but for the pupil to come to the teacher". Antoninus laughed, saying that it had been easier for Apollonius to come from Chalcis to Rome than from his house to the palace, and noted his greed for fees as well. This anecdote is the most famous about Apollonius, and characterises his Stoic dignity (or, on an unfriendly reading, his pride).

The satirical portrait in Lucian. Lucian, Demonax 31: Demonax sees Apollonius setting off with a crowd of disciples, summoned to the court as tutor to the emperor, and remarks: "There goes Apollonius with his Argonauts" (that is, gathered for the sake of the "golden fleece" — the fee). It is a satirical thrust against professional public philosophy for pay — a characteristic Cynic-Demonactean move against the entire "Stoic establishment" of the second century. The testimony to the paid character of Apollonius's teaching is reliable (Lucian here is not inventing the practice but only re-evaluating it ethically); the question of what this says about Apollonius's actual character is open. Marcus in 01-08 is the internal witness, directly correcting Lucian's external picture: "a man who counted his skill in transmitting doctrines as the least of his καλά."

Biographical details from Marcus himself. 01-08 is the unique text in which Marcus, as a direct witness, reports biographical details about Apollonius:

• Sharp pains — Apollonius bore them while remaining ἀεὶ ὅμοιος.
• The loss of a child — apparently Apollonius lost a child, and Marcus knew how he bore it (when is unknown).
• A long illness — Apollonius seems to have been ill for a long time and so remained ἀεὶ ὅμοιος.

The Greek puts this in general terms, so this is a conjecture, though a likely one. These three personal testimonies are unique: no other source on Apollonius preserves such details. They are known exclusively from Marcus, and are significant as internal evidence (against the external evidence of the SHA and of Lucian).

Educational role

Apollonius is a teacher of the second order for Marcus (after Junius Rusticus in 01-07). In the logic of 01-07 ↔ 01-08 the division of labour is the following:

• Rusticus (01-07): the doctrinal transmitter — corrects the adolescent philosophical disposition, hands on Epictetus's Discourses as a living canon, teaches accurate reading and slow assent.
• Apollonius (01-08): the existential witness — gives Marcus to see on a living example what Rusticus had given as texts. Marcus sees Apollonius in sharp pain, in mourning, in long illness — and is convinced that Stoic ἀπάθεια is not a theoretical description but a possible human state.

This existential component is what no text can replace: to be convinced of the reality of the Stoic ideal it is not enough to read about it; one has to co-present with someone who holds to it in a crisis. Without Apollonius Marcus would have had Epictetus's doctrine (through Rusticus), but not its empirical confirmation. This gives Apollonius a unique ontological function in the formation of Marcus.

The further qualities Marcus ascribes to Apollonius in 01-08:

• Non-aleatory firmness (ἀκύβευτος) — the anti-tyche programme of life.
• A single orientation to λόγος — without an alternative authority.
• The combination of σφοδρός and ἀνειμένος — firmness + softness in a single character.
• Not-peevishness in expositions — pedagogic ἀπάθεια.
• A modest estimate of his own pedagogical mastery.
• The art of receiving χάριτες from friends without losing ἐλευθερία.

• 01-08 — the principal, developed portrait of Apollonius; the unique text with the personal biographical details (loss of a son, long illness).
• 01-17 — thanks to the gods "that I knew Apollonius, Rusticus, Maximus."

• SHA Pius 10.4 — the anecdote of the refusal to appear at the palace first; the key prosopographical testimony.
• SHA Marcus 3.3 — Apollonius among Marcus's principal philosophical teachers.
• Lucian, Demonax 31 — the satirical portrait of "Apollonius and his Argonauts"; the obverse of the character, valuable as external testimony.
• PIR² A 933 — the standard prosopographical entry.
• A. Birley, Marcus Aurelius: A Biography, rev. ed., Routledge, 2000, ch. 3 ("Education") and passim — the reconstruction of Apollonius's role and his summons to Rome.
• A. S. L. Farquharson, The Meditations of the Emperor Marcus Antoninus, Oxford 1944, vol. II, ad 1.8 — the standard philological commentary.
• R. Hard, Marcus Aurelius: Meditations, OWC, Oxford 2011, notes ad 1.8.
• P. Hadot, The Inner Citadel, tr. M. Chase, Harvard 1998, ch. 2–3 — the general reconstruction of Marcus's educational biography, with discussion of Apollonius as "παράδειγμα ζῶν."