We know that Rusticus was appointed consul for the second time the year after Marcus was acclaimed emperor. He also served as urban prefect from 162 to 168 AD, effectively making him Marcus’s right-hand man at Rome during the first phase of his reign. Rusticus died shortly after this period, perhaps another victim of the plague, and Marcus asked the Senate to erect several statues in his honor. As with his other tutors, Marcus kept a statuette of Rusticus in his personal shrine and offered sacrifices to his memory. So that leaves us with an odd question: What exactly did Rusticus do to irritate the future emperor so badly?
The answer may lie in the nature of their relationship. Marcus tells himself in The Meditations that when learning to read and write you cannot be a teacher without having first been a student, and that this is even truer for the art of living.4 Students of Stoicism benefited from the wisdom of their teachers by treating them both as models, whose behavior they sought to emulate, and mentors, to whose advice they could listen. Rusticus certainly provided a living example of wisdom and virtue to Marcus. In The Meditations he mentions that Rusticus was one of three tutors, along with Apollonius of Chalcedon and Sextus of Chaeronea, who exemplified Stoicism for him as a way of life. He was also there to counsel him, though, offering guidance and moral correction. Indeed, Marcus said that it was Rusticus who showed him that he was in need of moral training and Stoic psychological therapy (therapeia). This may explain the tension in their relationship. Marcus clearly loved Rusticus dearly as a friend and looked up to him as a teacher, but he also found him exasperating at times, presumably because he frequently drew the young Caesar’s attention to flaws in his character.
We can perhaps infer which aspects of Marcus’s character Rusticus challenged based upon comments in The Meditations. For example, Rusticus taught him not to be pretentious, encouraging him to dress like a normal citizen when possible. He also taught Marcus to be a careful and patient student of philosophy, to read attentively rather than just skimming things, and not to be swayed too easily by speakers who have a silver tongue. Epictetus likewise told his students repeatedly that they should not speak about philosophy lightly, like the Sophists, but rather show its fruits in their very character and actions. In typically blunt fashion he told them that sheep don’t vomit up grass to show the shepherds how much they’ve eaten but rather digest their food inwardly and produce good wool and milk outwardly.5
The most important change Rusticus brought about, however, was that he persuaded Marcus to sideline the formal study of Latin rhetoric, expected of a Roman noble, in favor of a greater commitment to Stoic philosophy as a way of life. Rusticus the philosopher and Fronto the rhetorician, Marcus’s two most important tutors, appear to have vied for his attention for nearly a decade, but Rusticus finally won. Scholars date this “conversion” to around 146 AD, when Marcus was twenty-five. He confesses in a letter to Fronto that he has been unable to concentrate on his studies in Latin rhetoric. He is overcome with a mixture of joy and anguish after reading some books by a philosopher named Aristo. Most scholars believe this must have been Aristo of Chios, a student of Zeno’s who had rebelled against his teachings and adopted a simpler and more austere version of Stoicism resembling Cynicism. Perhaps Rusticus or one of his other Stoic tutors shared these writings with Marcus. Aristo rejected the study of logic and metaphysics, arguing that the primary concern of philosophers should be the study of ethics, an attitude we can find echoed in The Meditations.
Marcus told Fronto that Aristo’s writings tormented him, making him conscious of how far his own character fell short of virtue. “Your pupil blushes over and over again and grows angry with himself because, at the age of twenty-five, I have not yet absorbed any of these excellent teachings and purer principles into my soul.”6 The young Caesar was genuinely in turmoil. He felt depressed and angry and lost his appetite. He also mentions feeling envious of others, perhaps meaning that he yearned to dedicate himself to Stoicism and become like the philosophers he admired. It was around this time that Marcus began to distance himself from Sophists like Fronto and Herodes Atticus.
What was the process of being mentored by a Stoic philosopher actually like, though? Why did it have such a profound and lasting impact on Marcus? The Stoics wrote several books describing their psychotherapy of the passions, including one by Chrysippus, the third head of the school, titled The Therapeutics. Unfortunately, these are all lost to us today. However, a treatise titled On the Diagnosis and Cure of the Soul’s Passions survives, written by Marcus’s celebrated physician, Galen. A polymath with an eclectic taste in philosophy, Galen had initially studied under a Stoic called Philopater, and he drew upon early Stoic philosophy, quoting Zeno, in his own account of diagnosing and curing unhealthy passions. This may give us some clues about the nature of the Stoic “therapy” Marcus went through with Rusticus.
As a young man, Galen wondered why the Delphic Oracle’s maxim to “know thyself” should be held in such high regard. Doesn’t everyone already know himself? He gradually came to realize, though, that only the very wisest among us ever truly know ourselves. The rest of us, as Galen observed, tend to fall into the trap of supposing either that we are completely without fault or that our flaws are few, mild, and infrequent. Indeed, those who assume that they have the fewest flaws are often the ones most deeply flawed in the eyes of others. This is illustrated by one of Aesop’s fables, which says that each of us is born with two sacks suspended from our neck: one filled with the faults of others that hangs within our view and one hidden behind our back filled with our own faults. We see the flaws of others quite clearly, in other words, but we have a blind spot for our own. The New Testament likewise asks why we look at the tiny splinter of wood in our brother’s eye yet pay no attention to the great plank of wood obscuring our own view (Matthew 7:3–5). Galen says that Plato explained this well when he said that lovers are typically blind regarding the one they love. As we, in a sense, loves ourselves most of all, we are also most blind with regard to our own faults. The majority of us therefore struggle to attain the self-awareness required to improve our lives.
Galen’s solution to this problem is for us to find a suitable mentor in whose wisdom and experience we can genuinely trust. Anyone can tell when a singer is truly dreadful, but it takes an expert to notice very subtle flaws in a performance. Likewise, it takes a person of moral wisdom to discern slight defects in another person’s character. We all know that someone is angry when their face turns red and they start yelling, but a true expert on human nature would be able to tell when someone is just on the verge of getting angry, perhaps before they even realize it themselves. We should therefore make the effort to acquire an older and wiser friend: one renowned for honesty and plain speaking, who has mastered the same passions with which we need help, who can properly identify our vices and tell us frankly where we’re going astray in life. What Galen is describing sounds somewhat like the relationship between a modern-day counselor or psychotherapist and their client. However, a better comparison would probably be with the mentoring or “sponsorship” provided by recovering drug or alcohol addicts to those who are in recovery and struggling with similar habits—the help of a more experienced fellow patient, as Seneca puts it. Of course, finding an appropriate mentor is still easier said than done.