Philosophers are generally expected to display wisdom and calm in the face of existential questions. I am just not one of those philosophers. I spent 30 years racing away from these thoughts by running and swimming obsessively, pretending that I had no physical limits. Certain evasions are bound to fail: At 40, I suffered a cardiac arrest after an ill-advised treadmill workout. The sheer physicality of the event—the stopped heart, the failing body, the onerous recovery—threw into sharp relief a question that had always lurked beneath the surface: Does my life have a purpose? Or, put another way, how can I justify my existence? This dilemma gnaws at us in times of crisis and whispers to us in quiet moments of self-reflection. Rebecca Newberger Goldstein’s new book, The Mattering Instinct, helped me understand this feeling, to see it not as a personal quirk or a philosophical indulgence but as a fundamental aspect of what it means to be human. We are, Goldstein asserts, “creatures of matter who long to matter.” This phrase captures the central paradox of the human condition: We are physical beings governed by the indifferent laws of nature, yet we are consumed by an obsession with our own significance. Her book is about, as she puts it, “a missing piece in the puzzle of understanding ourselves, one another, and our troubled times.” Goldstein, a philosopher and novelist known for her ability to bridge the worlds of science and the humanities, undertakes an ambitious project. She seeks to trace the origin of this profound desire and redefine what it means for a human life to flourish. She comes to a somewhat-surprising conclusion: that happiness isn’t always attainable or even desirable, but that anyone can achieve a good life by working to create order out of nature’s chaos. Goldstein’s analysis hinges on an unexpected concept: the second law of thermodynamics. This is the principle of entropy, the inexorable tendency of any closed system to slide from order into chaos. Entropy is why houses fall into ruin, relationships fray, and bodies age. Life, in this framework, becomes a temporary act of defiance. Every living thing, Goldstein writes, is an intricate, energy-driven project engaged in a “ceaseless struggle against entropy.” Using the “mattering map”—a classification system Goldstein first developed in her 1983 novel, The Mind-Body Problem—she explains that this struggle manifests in different ways in different types of people. These types include the “heroic striver,” who believes the meaning of life is found in the next A+; the “transcender,” who seeks fulfillment in a relationship with the divine;  the “competitor,” who is motivated by defeating others; and the “socializer,” who seeks to matter by mattering to others.  I am—for better and occasionally for much worse—a heroic striver, which probably explains why I almost killed myself on that treadmill. We each resist entropy in our own way, but in every case we are enacting a primitive, biological imperative that Goldstein refers to as self-mattering. Every organism is metabolically programmed to prioritize its own survival. “Biology’s response to the supreme law of physics,” she writes, “is what makes self-mattering deeper than any instinct, making it, rather, the organizing principle behind all the instincts.” If our genes could speak, “they would make for the best of self-esteem coaches,” she imagines. They would “incessantly and urgently exhort the organism forward,” saying, “You are special, oh so special.” This universal drive is the raw material of our story, as Goldstein tells it, but it is not the finished product. The uniquely human drama begins when people start to reflect back on this instinct. [Read: What a cranky new book about progress gets right] This is the book’s central transformation. According to Goldstein, the leap from being simply a living thing to being a human occurs through the act of self-reflection, which turns us into what she dubs Homo iustificans—the creature who needs a reason. People’s capacity to “step back and survey themselves,” as the philosopher Thomas Nagel wrote, reveals a stark dissonance between our biological drive to survive and the fact that every life ends in death anyway. This realization gives rise to what Goldstein calls “the mother of all mattering questions—Do I matter?” The biological sense of importance is no longer enough. Instead, “We need to convince ourselves that our own self-mattering is warranted,” she writes. “We long to demonstrate that the reason we subjectively feel that we matter is that we objectively do.” That desire is what Goldstein defines as the “mattering instinct.” Here, Goldstein makes a pivotal philosophical claim: Our inherent human dignity lies not in some immutable essence like a soul or a divine image, but in this very struggle. Recasting the story of Eden—a world without entropy—she argues that the expulsion from paradise was not a fall but a step into humanity, the moment we became “values-seeking creatures.” Goldstein isn’t the first philosopher to argue that we are driven by the quest to justify our existence, but she sees it as an overriding instinct, even when our attempts are flawed or lead us astray. With this “mattering instinct” established as humans’ core driver, Goldstein redefines the goal of a well-lived life. She asks readers to look beyond what she considers a modern obsession with happiness, which she characterizes as a fleeting emotion, a mere “surge of neurotransmitters.” The true aim, she argues, is the richer, classical concept of “eudaimonia”—a deep and reflective sense that one’s life is being lived well. She borrows from Aristotle to underscore the point: Eudaimonia “is not found in amusement; for it would be absurd if the end were amusement, and our lifelong efforts and suffering aimed at amusing ourselves.” This thriving rests, instead, in feeling that our life is significant both to ourselves and to others. Crucially, this state of flourishing can, and often does, coexist with great suffering. To illustrate this, Goldstein turns to figures such as Ludwig Wittgenstein, who experienced constant mental anguish yet who exclaimed on his deathbed, “Tell them I’ve had a wonderful life.” This, Goldstein contends, was a statement not about happiness but about eudaimonia. His life, for all its misery, had been ferociously engaged in a mattering project: He developed what is arguably the most rigorous philosophical system of the 20th century, the goal of which was to understand the limits of language and thought. This heroic undertaking, which brought him no small amount of distress, gave Wittgenstein’s life coherence and purpose. Similarly, Goldstein examines the American philosopher William James, who had an existential crisis in his youth. In a thinly veiled anonymous account, James described the moment his sense of self collapsed: “Suddenly there fell upon me without any warning, just as if it came out of darkness, a horrible fear of existence,” he described it. “It was as if something hitherto solid within my breast gave way entirely, and I became a mass of quivering fear.” James’s recovery came from a decision to believe in his own “individual reality and creative power”—which contributed greatly to the field of empirical psychology, expanded American pragmatism, and reshaped theology in the 20th century. Both men struggled mightily in service of a project that made their lives feel not just bearable, but meaningful. Of course, certain mattering projects are ill-conceived from the start, as Goldstein shows through the story of the former white supremacist Frank Meeink. According to his book, Autobiography of a Recovering Skinhead, after severe emotional and physical abuse during his childhood left him feeling worthless, Meeink was desperate never to be a victim again. He found a perverse sense of belonging and destiny in the neo-Nazi skinhead movement, which convinced him that he was, as he put it, a “warrior” and that being white was “all that mattered,” turning his extreme self-doubt into destructive power. Later, while in prison, Meeink grew close with Black inmates. After his release, a Jewish employer showed him unconditional respect and helped replace his hate with constructive self-worth. Transformed by these experiences, Meeink ultimately channeled his need to matter into a heroic project: dedicating his life to fighting extremism. [Read: To get happier, make yourself smaller] If the mattering instinct originates in life’s resistance to entropy, then this same principle can help provide a standard for what Goldstein calls “getting mattering right.” A flourishing, morally good life, she proposes, is counter-entropic: It increases “the spread of flourishing, knowledge, love, joyfulness, peace, kindness, comity, beauty.” A life lived wrongly is one that aligns with entropy, increasing the world’s sum of chaos, cruelty, and dissolution. “People’s effects on entropy,” she states plainly, “provide the best overarching means I know to assess their lives.” Nowhere is this vision more powerfully embodied than in the subject of the book’s final portrait: Lou Xiaoying, an impoverished Chinese woman who survived by scavenging through rubbish and died around 2012. Over the course of her 88 years, she found and raised more than 30 abandoned baby girls left to die in dumpsters and on roadsides. As her adopted daughter Juju recalls, “If she had the strength enough to collect garbage, then how could she not recycle something as important as human lives?” Lou Xiaoying’s existence was one of almost uninterrupted  hardship, yet Juju describes her as happy, fulfilled by a purpose that was profoundly counter-entropic. She created life, connection, and love where society had left only waste and decay. The Mattering Instinct is a testament to the idea that humans find purpose when, as the poet Rumi wrote, we “let the beauty we love be what we do.” In a world fractured by competing claims on what’s important, Goldstein offers a vision that is both intellectually resonant and humane, reminding us that the struggle to justify our existence is the very thing that makes our existence matter.