Attestation and identification. Bacchius is a figure known exclusively from Marcus's mention at 01-06. No other biographical data survives.

The most plausible prosopographical identification (Birley 2000, Hadot 1998, Farquharson 1944) is with Bacchius the Platonist, mentioned by Galen as a philosophical teacher of the Middle Platonist era. If this identification is correct, Bacchius belonged to the Middle Platonism of the second century — to the intellectual circle that included Gaius (Γάϊος), Albinus, Atticus, and others. This would account for his being listed first in the sequence of teachers under Diognetus: the introduction to philosophy in the second century often began from the Platonic dialogues as propaedeutic (which agrees with the fact that Marcus, on his own testimony at 01-06, himself began in these same years to write dialogues — a genre Platonic in origin).

The identification, however, remains open: the name Βάκχειος / Βάκχιος was widespread in the Hellenistic world, and without further data the coincidence may be accidental. Hard in the OWC commentary: "the identification is plausible but not provable." Farquharson: "we cannot be certain."

Alternative identifications rejected by the modern consensus. Gataker and Casaubon in the seventeenth century proposed identifying Bacchius with Eutychius Proculus — the Latin grammarian mentioned in SHA Marcus 2.3 as one of Marcus's early tutors. The proposal is rejected on two grounds: (a) Eutychius was a grammarian, not a philosopher, whereas Bacchius at 01-06 is embedded in a philosophical sequence (οἰκειωθῆναι φιλοσοφίᾳ); (b) the proposal requires an unmotivated emendation of the manuscript reading. More in 01-06, the correction to Rogovin's footnote ¹⁰.

Other possible bearers of the name (Bacchius the physician of Tanagra, the Hellenistic commentator on Hippocrates; Bacchius the music theorist) do not fit chronologically or by discipline.

Educational role

If the identification with Bacchius the Platonist is correct, his role in the formation of Marcus is the introduction to the Platonic tradition still before the formal Stoic education. This corresponds to a common pedagogic sequence of the second century: adolescent reading of Plato (especially the early dialogues and the Republic) as a propaedeutic to the school-philosophy proper. Marcus, as is known, retained a lifelong familiarity with the Platonic corpus — the Meditations regularly contain quotations and reformulations of Plato (especially well known is the citation of Theaet. 174d at Med. 7.35 — "the view from above" as a philosophical exercise, see exercise). This Platonic leaven of the early formation remains in Marcus beneath the overlay of later Stoic orthodoxy.

In the composition of 01-06 Bacchius is the first of the three teachers Marcus enumerates as the philosophical mentors of his adolescence. On the principle of the catalogue's composition this apparently reflects either the chronological or the didactic primacy of Bacchius in the sequence (first Plato; then other, unestablished orientations under Tandasis and Marcianus).

• 01-06 — the sole mention.

• Galen, the mention of Bacchius the Platonist in the auto-bibliographical treatises (De libris propriis; De ordine librorum suorum) — if the identification is accepted.
• A. Birley, Marcus Aurelius: A Biography, rev. ed., Routledge, 2000, ch. 3.
• A. S. L. Farquharson, The Meditations of the Emperor Marcus Antoninus, Oxford 1944, vol. II, ad 1.6.
• R. Hard, Marcus Aurelius: Meditations, OWC, Oxford 2011, notes ad 1.6.
• J. Dillon, The Middle Platonists, 80 BC to AD 220, Duckworth 1977 — the general context of the second-century Middle Platonism, within which Bacchius the Platonist would have been active.