At once funny, wistful and unsettling, Sum is a dazzling exploration of unexpected afterlives—each presented as a vignette that offers a stunning lens through which to see ourselves in the here and now. In one afterlife, you may find that God is the size of a microbe and unaware of your existence. In another version, you work as a background character in other people’s dreams. Or you may find that God is a married couple, or that the universe is running backward, or that you are forced to live out your afterlife with annoying versions of who you could have been. With a probing imagination and deep understanding of the human condition, acclaimed neuroscientist David Eagleman offers wonderfully imagined tales that shine a brilliant light on the here and now.

“Eagleman is a true original. Read Sum and be amazed.” —Time Magazine

“This delightful, thought-provoking little collection belongs to that category of strange, unclassifiable books that will haunt the reader long after the last page has been turned. It is full of tangential insights into the human condition and poetic thought experiments. . . . It is also full of touching moments and glorious wit of the sort one only hopes will be in copious supply on the other side.” —The New York Times

Sum is an imaginative and provocative book that gives new perspectives on how to view ourselves and our place in the world.” —Alan Lightman, author of Einstein’s Dreams

“You will not read a more dazzling book this year than David Eagleman’s Sum. If you read it and aren’t enchanted I will eat 40 hats.” —Stephen Fry

“Delightful, thought-provoking . . . full of touching moments and glorious wit.” —Alexander McCall Smith, The New York Times Book Review

“As rigorous and imaginative as the writings of Italo Calvino and Alan Lightman.” —Nature

“Bracing, provocative, fun. . . . It challenges and teases as it spins out different parables of possibility.” —Houston Chronicle

“This is a scientist and exceptionally talented writer using the idea of the afterlife to reflect on our innermost fears and desires and also as a way of dissecting how we live.” —Tampa Tribune

“Teeming, writhing with imagination.” —Los Angeles Times

“David Eagleman’s Sum envisions a multiplicity of afterlives: pasts relived in shuffle mode, cast in the dreams of others, and dictated by our credit card reports.” —Vanity Fair

“Imaginative and inventive.” —Wall Street Journal

“It takes someone ridiculously smart to write something as deceptively simple as Sum.” —Denver Daily News

“With both a childlike sense of wonder and a trenchant flair for irony, the Baylor College of Medicine neuroscientist generously offers forty variations on the theme of God and the afterlife, imagining what each of us might find when we shuffle off this mortal coil.” —Texas Monthly

“A small gem of a book. . . . Who’d have thought that a young neuroscientist would have so much story in him?” —The Globe and Mail, Toronto

“Imaginative riffs that are simultaneously improvisational and well-considered. . . . Challenges you to leave well-traveled paths of belief and think in bold, new ways.” —Arizona Republic

“These images of the Great Beyond are more complex, sometimes whimsical, always veering off in an unexpected direction. In total they present a realm where you are certain to learn something about the life you just left behind.” —Deseret News

“With both a childlike sense of wonder and a trenchant flair for irony, the Baylor College of Medicine neuroscientist generously offers forty variations on the theme of God and the afterlife, imagining what each of us might find when we shuffle off this mortal coil. . . . Sum is great fun—sort of a brainy parlor game in print—and a modest satire aimed at zealots who define heaven and God to serve their own ends. It is also a reminder that when it comes to our knowledge of the hereafter, we have loads of faith but not a scintilla of proof.” —Texas Monthly

“Wow.” —New York Observer

“Stunningly original. . . . Sum has the unaccountable, jaw-dropping quality of genius.”—Geoff Dyer, The Observer

“Unsettling and reassuring, godly and godless. . . . Excitement pervades the whole volume.”—The National Post

Sum is terrific. It’s such a good idea that I was grinding my teeth all the way through wishing I’d thought of it first. The inventiveness, the clarity and wit of the prose, the calm air of moral understanding that pervades the whole thing, add up to something completely original. I hope Sum will be the great big hit it deserves to be.” —Philip Pullman, author of The Golden Compass

“Witty, bright, sharp and unexpected . . . as surprising a book as I’ve read for years.” —Brian Eno

“David Eagleman’s Sum is a captivating collection of vignettes that portray possible afterlives—creatively conceived and deftly described. Each tale imagines an unexpected reality that might await us, possible worlds that illuminate life with colors rarely encountered.” —Brian Greene, author of The Elegant Universe

Sum In the afterlife you relive all your experiences, but this time with the events reshuffled into a new order: all the moments that share a quality are grouped together.You spend two months driving the street in front of your house, seven months having sex. You sleep for thirty years without opening your eyes. For five months straight you flip through magazines while sitting on a toilet.You take all your pain at once, all twenty-seven intense hours of it. Bones break, cars crash, skin is cut, babies are born. Once you make it through, it’s agony-free for the rest of your afterlife.But that doesn’t mean it’s always pleasant. You spend six days clipping your nails. Fifteen months looking for lost items. Eighteen months waiting inline. Two years of boredom: staring out a bus window, sitting in an airport terminal. One year reading books. Your eyes hurt, and you itch, because you can’t take a shower until it’s your time to take your marathon two-hundred-day shower. Two weeks wondering what happens when you die. One minute realizing your body is falling. Seventy-seven hours of confusion. One hour realizing you’ve forgotten someone’s name. Three weeks realizing you are wrong. Two days lying. Six weeks waiting for a green light. Seven hours vomiting. Fourteen minutes experiencing pure joy. Three months doing laundry. Fifteen hours writing your signature. Two days tying shoelaces. Sixty-seven days of heartbreak. Five weeks driving lost. Three days calculating restaurant tips. Fifty-one days deciding what to wear. Nine days pretending you know what is being talked about. Two weeks counting money. Eighteen days staring into the refrigerator. Thirty-four days longing. Six months watching commercials. Four weeks sitting in thought, wondering if there is something better you could be doing with your time. Three years swallowing food. Five days working buttons and zippers. Four minutes wondering what your life would be like if you reshuffled the order of events. In this part of the afterlife, you imagine something analogous to your Earthly life, and the thought is blissful: a life where episodes are split into tiny swallowable pieces, where moments do not endure, where one experiences the joy of jumping from one event to the next like a child hopping from spot to spot on the burning sand.EgalitaireIn the afterlife you discover that God understands the complexities of life. She had originally submitted to peer pressure when She structured Her universe like all the other gods had, with a binary categorization of people into good and evil. But it didn’t take long for Her to realize that humans could be good in many ways and simultaneously corrupt and meanspirited in other ways. How was She to arbitrate who goes to Heaven and who to Hell? Might not it be possible, She considered, that a man could be an embezzler and still give to charitable causes? Might not a woman be an adulteress but bring pleasure and security to two men’s lives? Might not a child unwittingly divulge secrets that splinter a family? Dividing the population into two categories—good and bad—seemed like a more reasonable task when She was younger, but with experience these decisions became more difficult. She composed complex formulas to weigh hundreds of factors, and ran computer programs that rolled out long strips of paper with eternal decisions. But Her sensitivities revolted at this automation—and when the computer generated a decision She disagreed with, She took the opportunity to kick out the plug in rage. That afternoon She listened to the grievances of the dead from two warring nations. Both sides had suffered, both sides had legitimate grievances, both pled their cases earnestly. She covered Her ears and moaned in misery. She knew Her humans were multidimensional, and She could no longer live under the rigid architecture of Her youthful choices.Not all gods suffer over this; we can consider ourselves lucky that in death we answer to a God with deep sensitivity to the byzantine hearts of Her creations. For months She moped around Her living room in Heaven, head drooped like a bulrush, while the lines piled up. Her advisors advised Her to delegate the decision making, but She loved Her humans too much to leave them to the care of anyone else.In a moment of desperation the thought crossed Her mind to let everyone wait on line indefinitely, letting them work it out on their own. But then a better idea struck Her generous spirit. She could afford it: She would grant everyone, every last human, a place in Heaven. After all, everyone had something good inside; it was part of the design specifications. Her new plan brought back the bounce to Her gait, returned the color to Her cheeks. She shut down the operations in Hell, fired the Devil, and brought every last human to be by Her side in Heaven. Newcomers or old-timers, nefarious or righteous: under the new system, everyone gets equal time to speak with Her. Most people find Her a little garrulous and oversolicitous, but She cannot be accused of not caring.The most important aspect of Her new system is that everyone is treated equally. There is no longer fire for some and harp music for others. The afterlife is no longer defined by cots versus waterbeds, raw potatoes versus sushi, hot water versus champagne. Everyone is a brother to all, and for the first time an idea has been realized that never came to fruition on Earth: true equality.The Communists are baffled and irritated, because they have finally achieved their perfect society, but only by the help of a God in whom they don’t want to believe. The meritocrats are abashed that they’re stuck for eternity in an incentiveless system with a bunch of pinkos. The conservatives have no penniless to disparage; the liberals have no downtrodden to promote.So God sits on the edge of Her bed and weeps at night, because the only thing everyone can agree upon is that they’re all in Hell.Circle of FriendsWhen you die, you feel as though there were some subtle change, but everything looks approximately the same. You get up and brush your teeth. You kiss your spouse and kids and leave for the office. There is less traffic than normal. The rest of your building seems less full, as though it’s a holiday. But everyone in your office is here, and they greet you kindly. You feel strangely popular. Everyone you run into is someone you know. At some point, it dawns on you that this is the afterlife: the world is only made up of people you’ve met before.It’s a small fraction of the world population—about 0.00002 percent—but it seems like plenty to you.It turns out that only the people you remember are here. So the woman with whom you shared a glance in the elevator may or may not be included. Your second-grade teacher is here, with most of the class. Your parents, your cousins, and your spectrum of friends through the years. All your old lovers. Your boss, your grandmothers, and the waitress who served your food each day at lunch. Those you dated, those you almost dated, those you longed for. It is a blissful opportunity to spend quality time with your one thousand connections, to renew fading ties, to catch up with those you let slip away.It is only after several weeks of this that you begin to feel forlorn. You wonder what’s different as you saunter through the vast quiet parks with a friend or two. No strangers grace the empty park benches. No family unknown to you throws bread crumbs for the ducks and makes you smile because of their laughter.As you step into the street, you note there are no crowds, no buildings teeming with workers, no distant cities bustling, no hospitals running 24/7 with patients dying and staff rushing, no trains howling into the night with sardined passengers on their way home. Very few foreigners. You begin to consider all the things unfamiliar to you. You’ve never known, you realize, how to vulcanize rubber to make a tire. And now those factories stand empty. You’ve never known how to fashion a silicon chip from beach sand, how to launch rockets out of the atmosphere, how to pit olives or lay railroad tracks. And now those industries are shut down.The missing crowds make you lonely.You begin to complain about all the people you could be meeting. But no one listens or sympathizes with you, because this is precisely what you chose when you were alive.Descent of SpeciesIn the afterlife, you are treated to a generous opportunity: you can choose whatever you would like to be in the next life. Would you like to be a member of the opposite sex? Born into royalty? A philosopher with bottomless profundity? A soldier facing triumphant battles?But perhaps you’ve just returned here from a hard life. Perhaps you were tortured by the enormity of the decisions and responsibilities that surrounded you, and now there’s only one thing you yearn for: simplicity. That’s permissible. So for the next round, you choose to be a horse. You covet the bliss of that simple life: afternoons of grazing in grassy fields, the handsome angles of your skeleton and the prominence of your muscles, the peace of the slow-flicking tail or the steam rifling through your nostrils as you lope across snow-blanketed plains.You announce your decision. Incantations are muttered, a wand is waved, and your body begins to metamorphose into a horse. Your muscles start to bulge; a mat of strong hair erupts to cover you like a comfortable blanket in winter. The thickening and lengthening of your neck immediately feels normal as it comes about. Your carotid arteries grow in diameter, your fingers blend hoofward, your knees stiffen, your hips strengthen, and meanwhile, as your skull lengthens into its new shape, your brain races in its changes: your cortex retreats as your cerebellum grows, the homunculus melts man to horse, neurons redirect, synapses unplug and replug on their way to equestrian patterns, and your dream of understanding what it is like to be a horse gallops toward you from the distance. Your concern about human affairs begins to slip away, your cynicism about human behavior melts, and even your human way of thinking begins to drift away from you.Suddenly, for just a moment, you are aware of the problem you overlooked. The more you become a horse, the more you forget the original wish. You forget what it was like to be a human wondering what it was like to be a horse. This moment of lucidity does not last long. But it serves as the punishment for your sins, a Promethean entrails-pecking moment, crouching half-horse halfman, with the knowledge that you cannot appreciate the destination without knowing the starting point; you cannot revel in the simplicity unless you remember the alternatives. And that’s not the worst of your revelation. You realize that the next time you return here, with your thick horse brain, you won’t have the capacity to ask to become a human again. You won’t understand what a human is. Your choice to slide down the intelligence ladder is irreversible. And just before you lose your final human faculties, you painfully ponder what magnificent extraterrestrial creature, enthralled with the idea of finding a simpler life, chose in the last round to become a human.
© Mark Clark
Dr. DAVID EAGLEMAN is a neuroscientist and internationally best-selling author. He teaches brain plasticity at Stanford University, is the creator and host of the Emmy-nominated television series The Brain, and is the CEO of Neosensory, a company that builds the next generation of neuroscience hardware. The author of seven previous books, Eagleman lives in Silicon Valley in California.

Livewired: The Inside Story of the Human Brain
will be published by Pantheon Books in August of 2020. View titles by David Eagleman

About

At once funny, wistful and unsettling, Sum is a dazzling exploration of unexpected afterlives—each presented as a vignette that offers a stunning lens through which to see ourselves in the here and now. In one afterlife, you may find that God is the size of a microbe and unaware of your existence. In another version, you work as a background character in other people’s dreams. Or you may find that God is a married couple, or that the universe is running backward, or that you are forced to live out your afterlife with annoying versions of who you could have been. With a probing imagination and deep understanding of the human condition, acclaimed neuroscientist David Eagleman offers wonderfully imagined tales that shine a brilliant light on the here and now.

“Eagleman is a true original. Read Sum and be amazed.” —Time Magazine

“This delightful, thought-provoking little collection belongs to that category of strange, unclassifiable books that will haunt the reader long after the last page has been turned. It is full of tangential insights into the human condition and poetic thought experiments. . . . It is also full of touching moments and glorious wit of the sort one only hopes will be in copious supply on the other side.” —The New York Times

Sum is an imaginative and provocative book that gives new perspectives on how to view ourselves and our place in the world.” —Alan Lightman, author of Einstein’s Dreams

“You will not read a more dazzling book this year than David Eagleman’s Sum. If you read it and aren’t enchanted I will eat 40 hats.” —Stephen Fry

“Delightful, thought-provoking . . . full of touching moments and glorious wit.” —Alexander McCall Smith, The New York Times Book Review

“As rigorous and imaginative as the writings of Italo Calvino and Alan Lightman.” —Nature

“Bracing, provocative, fun. . . . It challenges and teases as it spins out different parables of possibility.” —Houston Chronicle

“This is a scientist and exceptionally talented writer using the idea of the afterlife to reflect on our innermost fears and desires and also as a way of dissecting how we live.” —Tampa Tribune

“Teeming, writhing with imagination.” —Los Angeles Times

“David Eagleman’s Sum envisions a multiplicity of afterlives: pasts relived in shuffle mode, cast in the dreams of others, and dictated by our credit card reports.” —Vanity Fair

“Imaginative and inventive.” —Wall Street Journal

“It takes someone ridiculously smart to write something as deceptively simple as Sum.” —Denver Daily News

“With both a childlike sense of wonder and a trenchant flair for irony, the Baylor College of Medicine neuroscientist generously offers forty variations on the theme of God and the afterlife, imagining what each of us might find when we shuffle off this mortal coil.” —Texas Monthly

“A small gem of a book. . . . Who’d have thought that a young neuroscientist would have so much story in him?” —The Globe and Mail, Toronto

“Imaginative riffs that are simultaneously improvisational and well-considered. . . . Challenges you to leave well-traveled paths of belief and think in bold, new ways.” —Arizona Republic

“These images of the Great Beyond are more complex, sometimes whimsical, always veering off in an unexpected direction. In total they present a realm where you are certain to learn something about the life you just left behind.” —Deseret News

“With both a childlike sense of wonder and a trenchant flair for irony, the Baylor College of Medicine neuroscientist generously offers forty variations on the theme of God and the afterlife, imagining what each of us might find when we shuffle off this mortal coil. . . . Sum is great fun—sort of a brainy parlor game in print—and a modest satire aimed at zealots who define heaven and God to serve their own ends. It is also a reminder that when it comes to our knowledge of the hereafter, we have loads of faith but not a scintilla of proof.” —Texas Monthly

“Wow.” —New York Observer

“Stunningly original. . . . Sum has the unaccountable, jaw-dropping quality of genius.”—Geoff Dyer, The Observer

“Unsettling and reassuring, godly and godless. . . . Excitement pervades the whole volume.”—The National Post

Sum is terrific. It’s such a good idea that I was grinding my teeth all the way through wishing I’d thought of it first. The inventiveness, the clarity and wit of the prose, the calm air of moral understanding that pervades the whole thing, add up to something completely original. I hope Sum will be the great big hit it deserves to be.” —Philip Pullman, author of The Golden Compass

“Witty, bright, sharp and unexpected . . . as surprising a book as I’ve read for years.” —Brian Eno

“David Eagleman’s Sum is a captivating collection of vignettes that portray possible afterlives—creatively conceived and deftly described. Each tale imagines an unexpected reality that might await us, possible worlds that illuminate life with colors rarely encountered.” —Brian Greene, author of The Elegant Universe

Excerpt

Sum In the afterlife you relive all your experiences, but this time with the events reshuffled into a new order: all the moments that share a quality are grouped together.You spend two months driving the street in front of your house, seven months having sex. You sleep for thirty years without opening your eyes. For five months straight you flip through magazines while sitting on a toilet.You take all your pain at once, all twenty-seven intense hours of it. Bones break, cars crash, skin is cut, babies are born. Once you make it through, it’s agony-free for the rest of your afterlife.But that doesn’t mean it’s always pleasant. You spend six days clipping your nails. Fifteen months looking for lost items. Eighteen months waiting inline. Two years of boredom: staring out a bus window, sitting in an airport terminal. One year reading books. Your eyes hurt, and you itch, because you can’t take a shower until it’s your time to take your marathon two-hundred-day shower. Two weeks wondering what happens when you die. One minute realizing your body is falling. Seventy-seven hours of confusion. One hour realizing you’ve forgotten someone’s name. Three weeks realizing you are wrong. Two days lying. Six weeks waiting for a green light. Seven hours vomiting. Fourteen minutes experiencing pure joy. Three months doing laundry. Fifteen hours writing your signature. Two days tying shoelaces. Sixty-seven days of heartbreak. Five weeks driving lost. Three days calculating restaurant tips. Fifty-one days deciding what to wear. Nine days pretending you know what is being talked about. Two weeks counting money. Eighteen days staring into the refrigerator. Thirty-four days longing. Six months watching commercials. Four weeks sitting in thought, wondering if there is something better you could be doing with your time. Three years swallowing food. Five days working buttons and zippers. Four minutes wondering what your life would be like if you reshuffled the order of events. In this part of the afterlife, you imagine something analogous to your Earthly life, and the thought is blissful: a life where episodes are split into tiny swallowable pieces, where moments do not endure, where one experiences the joy of jumping from one event to the next like a child hopping from spot to spot on the burning sand.EgalitaireIn the afterlife you discover that God understands the complexities of life. She had originally submitted to peer pressure when She structured Her universe like all the other gods had, with a binary categorization of people into good and evil. But it didn’t take long for Her to realize that humans could be good in many ways and simultaneously corrupt and meanspirited in other ways. How was She to arbitrate who goes to Heaven and who to Hell? Might not it be possible, She considered, that a man could be an embezzler and still give to charitable causes? Might not a woman be an adulteress but bring pleasure and security to two men’s lives? Might not a child unwittingly divulge secrets that splinter a family? Dividing the population into two categories—good and bad—seemed like a more reasonable task when She was younger, but with experience these decisions became more difficult. She composed complex formulas to weigh hundreds of factors, and ran computer programs that rolled out long strips of paper with eternal decisions. But Her sensitivities revolted at this automation—and when the computer generated a decision She disagreed with, She took the opportunity to kick out the plug in rage. That afternoon She listened to the grievances of the dead from two warring nations. Both sides had suffered, both sides had legitimate grievances, both pled their cases earnestly. She covered Her ears and moaned in misery. She knew Her humans were multidimensional, and She could no longer live under the rigid architecture of Her youthful choices.Not all gods suffer over this; we can consider ourselves lucky that in death we answer to a God with deep sensitivity to the byzantine hearts of Her creations. For months She moped around Her living room in Heaven, head drooped like a bulrush, while the lines piled up. Her advisors advised Her to delegate the decision making, but She loved Her humans too much to leave them to the care of anyone else.In a moment of desperation the thought crossed Her mind to let everyone wait on line indefinitely, letting them work it out on their own. But then a better idea struck Her generous spirit. She could afford it: She would grant everyone, every last human, a place in Heaven. After all, everyone had something good inside; it was part of the design specifications. Her new plan brought back the bounce to Her gait, returned the color to Her cheeks. She shut down the operations in Hell, fired the Devil, and brought every last human to be by Her side in Heaven. Newcomers or old-timers, nefarious or righteous: under the new system, everyone gets equal time to speak with Her. Most people find Her a little garrulous and oversolicitous, but She cannot be accused of not caring.The most important aspect of Her new system is that everyone is treated equally. There is no longer fire for some and harp music for others. The afterlife is no longer defined by cots versus waterbeds, raw potatoes versus sushi, hot water versus champagne. Everyone is a brother to all, and for the first time an idea has been realized that never came to fruition on Earth: true equality.The Communists are baffled and irritated, because they have finally achieved their perfect society, but only by the help of a God in whom they don’t want to believe. The meritocrats are abashed that they’re stuck for eternity in an incentiveless system with a bunch of pinkos. The conservatives have no penniless to disparage; the liberals have no downtrodden to promote.So God sits on the edge of Her bed and weeps at night, because the only thing everyone can agree upon is that they’re all in Hell.Circle of FriendsWhen you die, you feel as though there were some subtle change, but everything looks approximately the same. You get up and brush your teeth. You kiss your spouse and kids and leave for the office. There is less traffic than normal. The rest of your building seems less full, as though it’s a holiday. But everyone in your office is here, and they greet you kindly. You feel strangely popular. Everyone you run into is someone you know. At some point, it dawns on you that this is the afterlife: the world is only made up of people you’ve met before.It’s a small fraction of the world population—about 0.00002 percent—but it seems like plenty to you.It turns out that only the people you remember are here. So the woman with whom you shared a glance in the elevator may or may not be included. Your second-grade teacher is here, with most of the class. Your parents, your cousins, and your spectrum of friends through the years. All your old lovers. Your boss, your grandmothers, and the waitress who served your food each day at lunch. Those you dated, those you almost dated, those you longed for. It is a blissful opportunity to spend quality time with your one thousand connections, to renew fading ties, to catch up with those you let slip away.It is only after several weeks of this that you begin to feel forlorn. You wonder what’s different as you saunter through the vast quiet parks with a friend or two. No strangers grace the empty park benches. No family unknown to you throws bread crumbs for the ducks and makes you smile because of their laughter.As you step into the street, you note there are no crowds, no buildings teeming with workers, no distant cities bustling, no hospitals running 24/7 with patients dying and staff rushing, no trains howling into the night with sardined passengers on their way home. Very few foreigners. You begin to consider all the things unfamiliar to you. You’ve never known, you realize, how to vulcanize rubber to make a tire. And now those factories stand empty. You’ve never known how to fashion a silicon chip from beach sand, how to launch rockets out of the atmosphere, how to pit olives or lay railroad tracks. And now those industries are shut down.The missing crowds make you lonely.You begin to complain about all the people you could be meeting. But no one listens or sympathizes with you, because this is precisely what you chose when you were alive.Descent of SpeciesIn the afterlife, you are treated to a generous opportunity: you can choose whatever you would like to be in the next life. Would you like to be a member of the opposite sex? Born into royalty? A philosopher with bottomless profundity? A soldier facing triumphant battles?But perhaps you’ve just returned here from a hard life. Perhaps you were tortured by the enormity of the decisions and responsibilities that surrounded you, and now there’s only one thing you yearn for: simplicity. That’s permissible. So for the next round, you choose to be a horse. You covet the bliss of that simple life: afternoons of grazing in grassy fields, the handsome angles of your skeleton and the prominence of your muscles, the peace of the slow-flicking tail or the steam rifling through your nostrils as you lope across snow-blanketed plains.You announce your decision. Incantations are muttered, a wand is waved, and your body begins to metamorphose into a horse. Your muscles start to bulge; a mat of strong hair erupts to cover you like a comfortable blanket in winter. The thickening and lengthening of your neck immediately feels normal as it comes about. Your carotid arteries grow in diameter, your fingers blend hoofward, your knees stiffen, your hips strengthen, and meanwhile, as your skull lengthens into its new shape, your brain races in its changes: your cortex retreats as your cerebellum grows, the homunculus melts man to horse, neurons redirect, synapses unplug and replug on their way to equestrian patterns, and your dream of understanding what it is like to be a horse gallops toward you from the distance. Your concern about human affairs begins to slip away, your cynicism about human behavior melts, and even your human way of thinking begins to drift away from you.Suddenly, for just a moment, you are aware of the problem you overlooked. The more you become a horse, the more you forget the original wish. You forget what it was like to be a human wondering what it was like to be a horse. This moment of lucidity does not last long. But it serves as the punishment for your sins, a Promethean entrails-pecking moment, crouching half-horse halfman, with the knowledge that you cannot appreciate the destination without knowing the starting point; you cannot revel in the simplicity unless you remember the alternatives. And that’s not the worst of your revelation. You realize that the next time you return here, with your thick horse brain, you won’t have the capacity to ask to become a human again. You won’t understand what a human is. Your choice to slide down the intelligence ladder is irreversible. And just before you lose your final human faculties, you painfully ponder what magnificent extraterrestrial creature, enthralled with the idea of finding a simpler life, chose in the last round to become a human.

Author

© Mark Clark
Dr. DAVID EAGLEMAN is a neuroscientist and internationally best-selling author. He teaches brain plasticity at Stanford University, is the creator and host of the Emmy-nominated television series The Brain, and is the CEO of Neosensory, a company that builds the next generation of neuroscience hardware. The author of seven previous books, Eagleman lives in Silicon Valley in California.

Livewired: The Inside Story of the Human Brain
will be published by Pantheon Books in August of 2020. View titles by David Eagleman