“You have heard that it was said, ‘An eye for an eye and a tooth for a tooth,’ ” preaches Jesus of Nazareth in his Sermon on the Mount; “But I say to you, Do not resist an evildoer. But if anyone strikes you on the right cheek, turn the other also; and if anyone wants to sue you and take your coat, give your cloak as well; and if anyone forces you to go one mile, go also the second mile. Give to everyone who begs from you, and do not refuse anyone who wants to borrow from you.”9 This famous passage from the Gospel of Matthew is nothing less than a direct salvo against the most fundamental moral presumptions of the ancient world. Jesus of Nazareth quotes the Old Testament maxim “an eye for an eye” not as a call to vengeance, which is how we commonly misunderstand the phrase in today’s discourse. Rather, he invokes the phrase as a reference to the ancient social ideal of balanced justice.10 The Sermon preaches that true justice only exists in the heavenly realm and can never be achieved on earth. Worldly society should therefore build itself upon a different principle: agape.
In Christian writing, the Koine Greek word agape (α̉γάπη) signified more than its simple denotation of “love.” It represented a particular kind of lovingness—an unmitigated, boundless form of emotional identification with the other that was designed directly, in its expression, to break free from traditional moral limits and expectations.11 Early Christian writers seem to have chosen the word precisely because of its rarity in ancient usage. And in the Vulgate, St. Jerome (d. 420) translated agape into Latin with a similarly rare term in Western Roman usage: caritas.12
Augustine of Hippo, whose exegesis of the Sermon on the Mount would be authoritative for the duration of the European Middle Ages, took great interest in the underlying structures and mechanisms by which New Testament ethics worked. For Augustine, pre-Christian moral philosophy was not wrong; it was simply incomplete. As he explained, the ancient limit to violence that “an eye for an eye” represented was “a great step” (magnus gradus), for it kept revenge from exceeding injury. This was only the beginning of peace, however. “Perfect peace,” he continued, “is to have no desire at all for such revenge.”13
He described the dynamic between victim and attacker as a series of progressive increments that ultimately link the two together. The person who inflicts injury upon another without cause occupies the lowest step. On the next step is the person who refrains from inflicting unprovoked injury but who, when provoked, returns injury greater than what was inflicted. This is what “eye for an eye” is meant to correct, says Augustine. And it is an enlightened advance, he argues, because it requires restraint not to retaliate beyond due measure. The next two steps logically involve returning less than the injury inflicted and, finally, exacting no retribution at all.14 This act of exercising no retribution at all approaches what Jesus of Nazareth teaches, Augustine wrote, but even it does not suffice:
For it still appears a small matter to the Lord if you do not pay back the evil that you have received with no evil in return, unless you are prepared to receive more. For this reason he does not say, “But I say to you not to repay evil for evil,” even though this is a great command. Instead he says, “Do not resist evil in such a way that you not only do not repay the injury done to you but even so that you do not resist for fear that something else may be inflicted on you.” This is what he goes on to explain: But if anyone strikes you on the right cheek, offer him the other as well. He does not say, “If anyone strikes you, do not strike back,” but, “Present yourself again to the one who strikes you.”15
The call here, Augustine explains, is for a “perfected” morality in the same sense of the Latin that Dhuoda invoked for her son: a morality carried out to its fullest possible extreme, moving beyond the limits of “common” ethics toward ultimate completion.16 Humans were not only supposed to exact less vengeance or punishment than equal justice demanded; they were also not to exact any vengeance or punishment at all. Instead, they were to give further. If struck on the cheek by an offender, they were not to strike back, as balanced justice would sanction. They were to turn their other cheek toward their attacker and face a potential second attack. If an offender wished to take something by force, the victim was not supposed to take something from the offender in retaliation; the victim was to offer the offender even more in addition.
This state of perfection involved the achievement of deep emotional connection between the self and all others. “You have heard that it was said,” continues the Sermon on the Mount,
“You shall love your neighbor and hate your enemy.” But I say to you, Love your enemies and pray for those who persecute you, so that you may be children of your Father in heaven; for he makes his sun rise on the evil and on the good, and sends rain on the righteous and on the unrighteous. For if you love those who love you, what reward do you have? Do not even the tax-collectors do the same? And if you greet only your brothers and sisters, what more are you doing than others? Do not even the Gentiles do the same? Be perfect, therefore, as your heavenly Father is perfect.17
Many learn how to offer the other cheek to an attacker, Augustine wrote in reference to this passage, but few understand how to exhibit lovingness toward the one who wrongs them. For Augustine, the solution involved collapsing the boundaries between self and other entirely, allowing all human beings to recognize themselves as fellow creatures, regardless of station, regardless of friendship or enmity. To do so, one had to recognize, like a physician, an enemy’s ill will as a symptom of the soul’s sickness, finding connection through this recognition as one would with a rebellious child or stricken friend.18 “For indeed a human being, who is commanded by the lord of all even to love his enemies, ought to love another as much as he loves himself,” Augustine explained.19
In his De civitate Dei (“On the City of God”), a book so important to the Carolingian world that Einhard could claim it as Charlemagne’s favorite, Augustine connected caritas to two other ancient terms.20 The first was pietas.21 The Latin word pietas and the parallel Greek word eusebeia (εủσέβεια), Augustine wrote, are commonly understood to mean worship of God or duty toward one’s parents. In the everyday vernacular, however, he continued, pietas refers to works of misericordia.22 These notions of interconnectedness between caritas, pietas, and misericordia would govern discourses of other-oriented emotion and fellow-feeling for the rest of the Middle Ages.
Augustine’s emphasis on the association between caritas, pietas, and misericordia in De civitate Dei was composed in direct reference to a debate within Stoic philosophy about the proper balances to which a society should adhere in its regulation of justice. Seneca the Younger (d. 65) had taught that true justice could only be reached through a proper balance of severity and leniency. His term for ideal leniency in the service of justice was clementia, the root of the modern English word “clemency.” For Seneca, clementia entailed “restraint of the mind when it is able to take revenge, or the leniency of the more powerful party towards the weaker in the matter of settling penalties,” a definition readily quoted throughout the Middle Ages.23 Articulating a common Stoic position, he believed that the essential nature of all humans was to be emotionally peaceful and nonviolent. Humans in the right state of mind are the gentlest creatures in existence, he wrote in his treatise, De ira (“On Anger”), embodying the opposite of anger:
What is more inclined to love others than a human? What is more hostile than anger? The human