What would Aristotle make of Yom Kippur? He would probably struggle with the Hebrew, and be bemused by the strange ways of the Jews. But at the holiday’s apogee, during the recitation of the haunting Unetaneh Tokef, he would experience an unnerving moment of déjà vu—for its central message is precisely that of his own moral philosophy.Unetaneh Tokef is one of the most sublime texts in the Rosh Hashanah and Yom Kippur liturgies. It begins with the trembling of guilty angels as God opens the Book of Remembrances. It continues with God inscribing people’s fates for the next year as they proceed before him. And it concludes with an entreaty for forgiveness and the exaltation of God’s name. At its climax, it contains the following passage:On Rosh Hashanah will be inscribed and on Yom Kippur will be sealed…\nWho will live and who will die—\nWho at his time, and who before his time—\nWho by water and who by fire…\nWho will rest and who will wander;\nWho will live in harmony and who will be buffeted;\nWho will enjoy tranquility and who will suffer;\nWho will be impoverished and who enriched;\nWho will be degraded and who exalted.\nBut repentance and prayer and charity will make the Decree less bad.This final line is the fulcrum around which the text’s meaning revolves. According to some mistranslations, repentance, prayer, and charity are said to “avert the bad Decree,” but in Hebrew, it is quite plain that it is the badness (the ro’ah) of the Decree, and not the Decree itself, that is averted. The blow will come, but when it does, something can soften it.We cannot necessarily prevent bad things happening to us, the liturgy suggests. Although our choices can greatly influence the paths our lives take, we cannot immunize ourselves from every possible external shock. We cannot control the future. But we can control how it controls us. By leading our lives in a certain way, we can regulate how we experience those bad things when they strike. We can decide whether we will let them destroy us, or whether we will emerge from them stronger. Subversively, the prayer suggests that we have the power, by choice, simply to experience bad things as being less bad.In other words: We cannot stop life throwing lemons at us, but we can stop ourselves being bruised by the flying lemons, and even make lemonade. And with this empowering message, Unetaneh Tokef appeals for Jews to embrace a lesson first laid down by Aristotle, just before the conquest of ancient Israel by Alexander the Great.Aristotle is the father of Virtue Ethics, one of the three great ethical traditions in Western philosophy. For consequentialists, acts are right inasmuch as they bring about the best consequences. Deontologists judge the rightness of acts in terms of their adherence to certain rules: The Ten Commandments forbid murder, for instance, and it is never permissible to murder for the sake of expected benefits. Virtue Ethics offers a different answer because it is a response to a different question. Instead of focusing on what one should do, Virtue Ethics is concerned more broadly with how one should live. The purpose of the philosophy is to offer guidance for a good life. The choices it guides concern not our specific actions, but our way of life. It is concerned with forming upstanding characters and cultivating an intuition for a sense of right and wrong that cannot necessarily be articulated in simple rules.In The Nicomachean Ethics, Aristotle argues that the ultimate good is eudaemonia—ordinarily translated as “happiness” but referring not to a transient feeling of joy but to a type of flourishing that characterizes a person throughout his lifetime. He argues that such eudaemonia is achieved by cultivating certain virtues or character traits, such as courage, truthfulness, justice, compassion, and generosity. These virtues cannot be learned by rote, but are best acquired through practice. By consistently acting like good people, argues Aristotle, we turn into good people.And good people, in turn, are happy. They thrive. In part, that is because Aristotle simply believes that what it means to flourish is to exercise one’s rational faculties through virtue. But there is another, more powerful interpretation.By cultivating these virtues, we enable ourselves to take whatever fate has to throw at us. By forming the right character, we immunize ourselves against the vicissitudes of fortune. We ensure that our happiness is not dependent on the good hand that fate deals us, but on our ability to play whatever hand we are dealt. We develop a healthy mind-set and outlook, so that when the going gets tough, we will endure and persevere.Aristotle is quite clear: Happiness is too important to be left to luck. It is dangerous to rely for one’s happiness on factors that one cannot control, such as wealth or on health. The one thing we can control is our own disposition. If we act virtuously, he writes in The Nicomachean Ethics, we prime ourselves to have an “element of stability” that will enable us to “bear changes of fortunes most nobly, and with perfect propriety.” When we suffer terrible misfortunes, instead of breaking down, we will be able to endure them “with patience.”By acting virtuously, we can become unflappable. We become empowered to endure tragedy with a certain diffidence because the source of our happiness is internal. We develop an ability to lead a good life, even if nothing good happens to us, because we have a strength of character that drowns out the effects of hardships. “No supremely happy man,” writes Aristotle, “can ever become miserable.”Historically, it is unsurprising that this Aristotelian worldview should have wended its way into the Jewish liturgy. When Unetaneh Tokef was written, at some point from the seventh century CE onward, Jews would have been familiar with popular forms of Greek philosophy. In particular, the dominant Stoic school of thought held that inner peace and equanimity of mind were the keys to well-being, enabling one to suppress suffering in times of adversity. In following centuries, the great Jewish philosopher Maimonides assimilated Aristotle’s theories on virtues into Jewish theology, seeing the cultivation of appropriately balanced character traits as an imitation of God himself.In modern times, this facet of Aristotle’s philosophy finds expression, surprisingly, in the writings of Lebanese-American author Nassim Nicholas Taleb (of The Black Swan fame). In Antifragile, Taleb argues that everything in the world falls into three types. Things that break when subjected to shock, force, and volatility—like fine-bone china—are fragile. Things that survive when attacked are robust. And those that can be subjected to stress and emerge even stronger, like human muscle, are antifragile. In Taleb’s thinking, individuals and societies should strive to be antifragile. We render ourselves vulnerable to debilitating shocks if we run away from difficult challenges. But if we learn to handle setbacks as opportunities, we can, to quote Jewish liturgy, make the bad Decree less bad.So how might prayer, repentance, and charity specifically—with a little help from Aristotle—make the bad Decree less bad? Prayer, repentance, and charity are obviously not tokenistic gestures that can ward off evil. The Hebrew prophets themselves railed against the pagan belief that mere acts of ritual and worship can give humankind mastery over the natural world, arguing instead that only a culture of justice and compassion could give society the necessary resilience (or antifragility) to survive.Character changes the way we perceive the world, and hence how we interact with it. Through prayer, we cultivate faculties for thoughtful reflection and sincere introspection, for patience and magnanimity. Through repentance, we learn from our mistakes and steady ourselves not to repeat them, developing an instinctive grasp for how to respond when things go wrong. And through charity, we inculcate in ourselves an ability to let go, and a willingness not to be perpetually preoccupied with gain.There will be times in our lives when those dear to us will die before their time, and when we will be fated to wander or suffer, or be buffeted or degraded. That is not up to us. But whether such episodes are followed by prolonged periods of agony, self-pity, and doubt is in our hands. When God signs the Book of Remembrances, he can only seal part of our fate: The rest is up to us as rational creatures, and beyond his control.