Marcus wrote that anyone who truly wants to achieve wisdom through Stoicism will make it his priority in life to cultivate his own character and seek help from others who share similar values.7 That seems like the role Junius Rusticus played for him. We should ask that person if they notice any unhealthy passions in us, says Galen, assuring them that we’re not going to be offended if they speak frankly. Galen also explains that the novice is bound to feel that some of his mentor’s observations are unfair, but he must learn to listen patiently and take criticism on the chin without becoming irritated. From what Marcus says, that was probably quite challenging for him at first, although Rusticus was good at smoothing things over.
Marcus had another Stoic tutor, called Cinna Catulus, about whom we know very little. Marcus observed that Catulus was a man who paid attention to his friends when they found fault in his character; even if they did so unjustly, he would always try to address matters and restore their friendship.8 Through their own behavior, therefore, Rusticus and Catulus both showed Marcus that a wise man should welcome criticism from his friends.
The Stoics clearly inherited their love of plain speaking from their predecessors the Cynics, who were renowned for speaking very bluntly and criticizing even powerful rulers. In a sense, it was the duty, and privilege, of a true philosopher to speak truth to power. One of the most famous legends about Diogenes the Cynic tells how Alexander the Great sought out the philosopher. It’s a juxtaposition of opposites: Diogenes lived like a beggar, and Alexander was the most powerful man in the known world. However, when Alexander asked Diogenes if there was anything he could do for him, the Cynic is supposed to have replied that he could step aside, as he was blocking the sun. Diogenes could speak to Alexander as if they were equals because he was indifferent to wealth and power. Alexander is said to have walked off and returned to his conquests, apparently without having gained much wisdom.
As was often the case, the Stoics adopted a more moderate approach, and they were concerned that their speech should not only be honest and simple but also appropriate to the needs of the hearer. There’s no point in speaking plainly to people if it doesn’t benefit them. Throughout The Meditations, Marcus makes many references to the value he places on speaking the truth, but he also consistently recognizes the importance of communicating it appropriately. For instance, Alexander of Cotiaeum, his childhood grammarian, made a lifelong impression on Marcus by the tactful way he would correct those making a verbal error.9 If someone used a word incorrectly, Alexander would not overtly criticize the speaker. He never interrupted them or challenged them on the spot. Instead, the grammarian had a more artful and indirect way of steering them in the right direction. Marcus noticed that Alexander would subtly drop in the correct expression while replying or discussing some other topic. If the real goal for Stoics is wisdom, then sometimes just blurting out the truth isn’t enough. We have to put more effort into communicating with others effectively.
Diplomacy was, of course, particularly important to Marcus. His duties as Caesar and later as emperor involved handling highly sensitive discussions, such as negotiations over peace treaties with foreign enemies. We can clearly see from his personal correspondence that he was a charming and tactful man with an impressive ability to resolve conflicts between his friends. Indeed, Fronto waxes lyrical about this, extolling his young student’s ability to unite all his friends together in harmony, something the rhetorician compares to the mythic power of Orpheus to tame savage beasts through the music of his lyre. Throughout Marcus’s reign, he doubtlessly averted many serious problems through his patient diplomacy and sensitive use of language. Indeed, he even reminds himself that he should always be tactful and honest with whoever he’s speaking to, especially in the Senate.10
In addition to having this innate talent, Marcus learned a great deal from the Stoics about how a wise man should try to communicate with others. Apollonius of Chalcedon, for instance, was not a man to hold back his words, yet he balanced his self-confidence with open-mindedness. Marcus describes how another of his most beloved teachers, Sextus of Chaeronea, came across as both very serious and plainspoken, yet he was exceptionally patient with the unlearned, and even the opinionated. Correcting someone else’s vices, Marcus says, is like pointing out that they have bad breath—it requires considerable tact. However, he noticed that Sextus won the respect of all sorts of people by skillfully adapting his conversation so that it seemed more charming than any flattery, even while he was speaking frankly or disagreeing with them. Clearly, Stoics like Marcus placed a lot more value on manners and civility than the Cynics did. The Stoics realized that to communicate wisely, we must phrase things appropriately. Indeed, according to Epictetus, the most striking characteristic of Socrates was that he never became irritated during an argument. He was always polite and refrained from speaking harshly even when others insulted him. He patiently endured much abuse and yet was able to put an end to most quarrels in a calm and rational manner.11
We can imagine that when Rusticus challenged Marcus over his behavior, his remarks, though sometimes provocative and close to the bone, were probably judicious enough that his young student benefited from them without feeling humiliated. How can we find mentors with such tact, though? Galen admits that you’re not likely to meet many people like Diogenes the Cynic, who was brave enough even to speak plainly to Alexander the Great. What’s required first is a more general openness to criticism: we should give everyone we meet permission to tell us what our faults are, according to Galen, and resolve not to be angry with any of them. Indeed, Marcus tells himself both to enter into every man’s mind, to study their judgments and values, and to let every man enter into his.12 If anyone gives him a valid reason to believe that he’s going astray in terms of either thought or action, he says he will gladly change his ways. Marcus sought to make it his priority in life to get to the truth of matters, reminding himself that nobody has ever really been harmed in this way but that those who cling to error and ignorance harm themselves.13 We’re told this advice goes back to Zeno. Most men are eager to point out their neighbors’ flaws, he said, whether we ask them to or not. So instead of resenting it, we should welcome criticism from others as one of life’s inevitabilities and turn it to our advantage by making all men into our teachers. Galen therefore says that if we desire to learn wisdom, we must be ready to listen to anyone we encounter and show gratitude “not to those who flatter us but to those who rebuke us.”14
This doesn’t mean we should trust all opinions equally, of course. Marcus makes it clear that we must train ourselves to discriminate good advice from bad and learn not to preoccupy ourselves with the opinions of foolish people. It’s prudent to listen carefully to most of the people we meet in life but not to give equal weight to all opinions. Rather, by welcoming criticism and accepting it dispassionately, we can gradually learn to sort through it rationally and discern good advice from bad. Sometimes, indeed, we learn most from the mistakes of others. However, as Galen observes, we should place more trust in the counsel of individuals who provide us with consistent evidence of their wisdom and virtue. Nevertheless, if we exercise caution we can learn from all people while we look for someone like Rusticus, a friend whose wisdom we can trust implicitly.