Family background: the dynasty of Stoic opposition. Rusticus belonged to a family that had been part of the "Stoic opposition" of the first century — the line of Roman senator-Stoics who voiced moral criticism of the principate from Nero through Domitian. His grandfather is Q. Junius Arulenus Rusticus, friend and follower of Thrasea Paetus; tribune of the plebs in 66, praetor in 69, suffect consul about 92; he wrote a laudatory life of Thrasea (and, on some testimonies, of Helvidius Priscus too), for which Domitian executed him in 93 in the course of the repressions against the philosophers (the expulsion of the philosophers from Rome, the execution of Arulenus, Herennius Senecio, the exile of Epictetus). This line — Thrasea Paetus → Helvidius Priscus → Arulenus Rusticus → Herennius Senecio — was the canonical Stoic martyrology by the beginning of the second century (see Tac. Agr. 2; Hist. 4.5–8).

Junius Rusticus the philosopher thus inherited the direct Stoic tradition of resistance and the canonical texts of this line (including the Vita Thraseae and the Vita Helvidii). Under Antoninus Pius and Marcus the family was rehabilitated, and Rusticus-the-grandson came to a standing far surpassing what his grandfather had not been allowed to attain.

Career under the Antonines. Rusticus's senatorial career can be reconstructed only in general outline. Two peaks are secure:

• Ordinary consul of 162 — Rusticus's second consulship (SHA Marcus 3.3: "consulem iterum designavit"); his colleague was L. Titius Plautius Aquilinus. This was the first year of the joint reign of Marcus and Lucius Verus, after the death of Antoninus Pius in 161; a second consulship, and an ordinary one, was a high mark of favour.
• Praefectus urbi under Marcus, holding the office apparently for a considerable period (on one reconstruction from 162 almost to the end of the 160s). The city prefecture is the highest urban magistracy, the chair of the senatorial court, effectively the head of the Roman capital's administration.

Marcus and Rusticus: a long relationship. Rusticus's tutelage over Marcus, which probably began in Marcus's adolescent and young-adult years (the mid-to-late 130s), did not break off with Marcus's accession. Capitolinus (SHA Marcus 3.3) observes that Marcus consulted Rusticus on all public and private matters, always kissed him in greeting before the praetorian prefects, and after his death asked the senate for statues in his honour. This is a continuing presence: not a teacher of youth, but the permanent counsellor of the ruler.

Rusticus and the trial of Justin Martyr. Around 165 (the precise dating is disputed, the range is c. 162–168) the prefect of the city, Rusticus (identified with Junius Rusticus), presided over the trial of Justin Martyr — the Christian apologist, author of the first and second Apologies, addressed to Antoninus Pius and Marcus respectively — and condemned Justin and his disciples to death for the confession of Christianity. The Acta Iustini (the martyrological acts) preserve the protocol of this trial. The episode is historically weighty and philosophically uncomfortable: the principal Stoic teacher of the "philosopher on the throne" Marcus turned out to be the magistrate who executed the founding figure of second-century philosophical Christianity. In the Meditations Marcus mentions the Christians only once (Med. 11.3) — and with manifest incomprehension.

Educational role

Rusticus is the principal doctrinal teacher of Marcus in the Stoic tradition. The division of labour between Diognetus and Rusticus, as it lies in 01-06 ↔ 01-07, is the following:

• Diognetus (01-06): adolescent philosophical initiation — the disposition of scepticism toward charlatanism, openness to παρρησία, introduction to οἰκείωσις with philosophy, the visible ascetic habitus, the first teachers.
• Rusticus (01-07): the mature school-correction of that initiation — against σοφιστικός ζῆλος, against the writing of doctrinal treatises, against publicistic protreptic, against ostentatious asceticism; on the positive side: accurate reading, slow συγκατάθεσις, simplicity in self-presentation, the capacity for reconciliation, and — above all — access to the Epictetan Discourses from Rusticus's own library.

This last detail is pivotal. Before Rusticus Marcus apparently did not have his own copy of the Diss.; after Rusticus, Epictetus becomes the principal cited author in the Meditations (Marcus cites him repeatedly; cf. in particular Med. 11.33–39, where a selection of Epictetan formulae is gathered). Rusticus thus does not merely teach Marcus Stoicism in oral lessons, but passes on a living canon in the form of a book to which Marcus then returns throughout his life.

The correction of the "Greek asceticism." Marcus's adolescent asceticism of 01-06 (σκίμπους + δορά + the cloak, only at his mother's urging did he agree to sleep on a couch spread with skins, per SHA Marcus 2.6) is the very ostentatious ascesis against which Rusticus in 01-07 warns. Rusticus thus corrects Marcus's first philosophical experience: the ascetic instinct is right, but its visible demonstration is a sophistic trap. The mature Marcus of the Meditations is private, simple, without a public philosophical persona; this is Rusticus's work.

• 01-07 — the principal, developed portrait; one of the longest entries of Book I.
• 01-17 — thanks to the gods "that I knew Apollonius, Rusticus, Maximus," and that "though I was often out of humour with Rusticus, I never did anything of which I had occasion to repent."

• SHA Marcus 3.3 — Rusticus among the principal philosophical teachers of Marcus; his counsel, the kiss of greeting, the second consulship, the statues after his death.
• Dio Cassius 71.35 — Rusticus among Marcus's teachers.
• Tacitus, Agricola 2; Historiae 4.5–8 — the related Stoic martyrological line (Thrasea Paetus, Helvidius Priscus, Arulenus Rusticus).
• Acta Iustini (Acts of the Christian Martyrs, ed. Musurillo) — the protocol of the trial of Justin Martyr and his disciples under the presidency of the prefect Rusticus.
• PIR² I 815 — the standard prosopographical entry.
• A. Birley, Marcus Aurelius: A Biography, rev. ed., Routledge, 2000, ch. 3 ("Education") and passim — the reconstruction of Rusticus's role, of his political career, and of his relations with the emperor Marcus.
• A. S. L. Farquharson, The Meditations of the Emperor Marcus Antoninus, Oxford 1944, vol. II, ad 1.7 — the standard philological commentary on Med. 1.7.
• R. Hard, Marcus Aurelius: Meditations, OWC, Oxford 2011, notes ad 1.7.
• P. Hadot, The Inner Citadel, tr. M. Chase, Harvard 1998, especially ch. 3 ("The Discourses of Epictetus") — the analysis of the role of the Epictetan Discourses in the formation of Marcus and of the significance of the transmission through Rusticus.
• M. Griffin, "Iure plectimur: The Roman Critique of Roman Imperialism," PCPS 28 (1982) — an analysis of the first-century Stoic opposition as context for the inheritance of Rusticus.
• C. Edwards & G. Woolf (eds.), Rome the Cosmopolis, Cambridge 2003 — the context of the philosophical circles of the second century.