now revised, and with a new introduction by the author

Pop anthropologists claim, oh, happy refrain,
man's defined by tools.
Tools help us abide
ol'entropy's tide,
But even
they obey the rules!
The Practice Effect

revised and with a new introduction, 2020

DAVID BRIN's Practice Effect cover for revised edition

original Bantam 1984 edition cover

DAVID BRIN's Practice Effect cover for 1984 original edition

does practice make perfect?

"He tried to remember a few facts from the linguistics course he had taken in college in order to get out of the infamous Professor LaBelle's English 7. There were a few sounds, he had learned, that were nearly universal in meaning among human beings. Anthropologists used to use them at the beginning of contact with newly discovered tribes. He swallowed, then ventured one of them. 'Huh?' he said." — The Practice Effect

Physicist Dennis Nuel was the first human to probe the strange realms called anomaly worlds — alternate universes where the laws of science were unpredictably changed.

But the world Dennis discovered seemed almost like our own — with one perplexing difference. To his astonishment, he was hailed as a wizard and found himself fighting beside a beautiful woman with strange powers against a mysterious warlord as he struggles to solve the riddle of this baffling world.

Read the first 2 chapters online, or scroll down to purchase THE PRACTICE EFFECT.

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more about The Practice Effect

practicing puns

The chapter titles for The Practice Effect are jokes, mostly puns. In order, with explanations:

  • Sooee Generis (like 'Sui Generis' but with the pig-caller's noise)
  • Cogito, Ergo Tutti Fruitti (I think, therefore tutti fruitti)
  • Nom de Terre (tr. 'name of the land' but in the context of the chapter a play on 'Nom de Guerre')
  • The Best Way to Carnegie Hall (... is practice)
  • Transom Dental (a play on 'transcendental')
  • Ballon d'Essai (tr. 'trial balloon')
  • Pundit Nero (Pandit Nehru, first Prime Minister of India)
  • Eurekaarrgh (a more accurate variation of 'eureka')
  • Discus Jestus (majesty disc)
  • Sic Biscuitus Disintegratum (or 'this is how the cookie crumbles')
  • Et Two Toots (or 'Et tu, Brute?')
  • Semper Ubi Sub Ubi (tr. 'always where under where' but in the context of the chapter, 'always wear underwear')

  • foreign-language editions

    Here are some of the covers of The Practice Effect's foreign and foreign-language publications.

    The Practice Effect's foreign editions

    can you 'practice'?

    Want to try out the 'practice effect' in this universe? Take a look at this page evaluating agile vs. scrum vs. waterfall vs. kanban.

    The Practice Effect in the world

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    Queries about film or media rights to any DAVID BRIN books or stories can be addressed to his film agent:
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    The Practice Effect reviews

    Publishers Weekly

    "Reminiscent of the freewheeling, high-spirited alternate world novels of the '40s ... Lively, outlandish and entertaining." review

    "David Brin's The Practice Effect is the reason I began reading everything I could find by this author. Brin has taken a single premise (what if one of the laws of thermodynamics were repealed?), and woven it into a clever tale of a world of practical magic.... Further, the central concept of the novel makes explicit the crucial difference between creators and users."

    Isaac Asimov's Science Fiction Magazine

    "High spirits and inventiveness ... Dennis's adventures, which can only be called rollicking, are legion."

    Goodreads community review

    "It started off feeling a lot like John Carter from A Princess of Mars meets A Connecticut Yankee in King Arthur's Court. By the end I added a good dose of the movie Speed to the mix. That pretty much sums it up. Except for one thing that made it exceptional — the practice effect. I love when an author comes up with a really original idea that would deeply influence how things turned out in the world and follows it through. It turned a really basic and frequently used idea, that of the modern man or scientist who finds himself in a society that has little or no technology, and turned it into something interesting."

    No Wasted Ink review

    "This is a clear forerunner to his development of science to propel the plot in his later novels. The concept of the practice effect itself makes this novel one that you should take a look at in addition to Brin's other more well known works. To me it was as if the world was a character all unto itself. I kept wanting to see more of how the practice effect changed the lives of these people. Although I read this novel many years ago, I have never forgotten it and I feel it is a work that needs to be called attention to. Otherwise, you might miss out on a truly unique science fiction experience." customer review

    "Gee, not every SF book has to be a deep exploration of the limits of the genre. Sometimes you just like to kick back and enjoy yourself. This is exactly what this book is, and it's a great read, fast and fun at the same time, while still throwing up some interesting concepts."

    Poul Anderson

    "A delightful, often very witty story, with the underlying thoughtfulness we expect from David Brin."

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    David Brin's science fiction novels have been New York Times Bestsellers, winning multiple Hugo, Nebula and other awards. At least a dozen have been translated into more than twenty languages. They range from bold and prophetic explorations of our near-future to Brin's Uplift series, envisioning galactic issues of sapience and destiny (and star-faring dolphins!). Learn More

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    reviews and recommendations

    Vernor Vinge

    "More than any writer I know, David Brin can take scary, important problems and turn them sideways, revealing wonderful opportunities. This talent shows strongly in Kiln People, a novel which is deep and insightful and often hilarious, all at the same time."

    praise for Heart of the Comet

    "A magnificent effort ... their story gets better, and better, and better."
    — Locus

    praise for Earth

    "Brin is a physicist of note who has been a NASA consultant, and he knows how to turn the abstractions of particle physics into high adventure.... He excels at the essential craft of the page-turner, which is to devise an elegantly knotted plot that yields a richly variegated succession of high-impact adventures undergone by an array of believably heroic characters."
    — Thomas M. Disch,

    praise for Sundiver

    "The original Progenitors have long disappeared, and the intergalactic search for relics of their presence, along with the conflicts generated by humanity's asserted uniqueness, shapes much of the sequence, which Brin enlivens throughout with exceedingly clever depictions of a wide range of Alien species."
    — John Clute, The Encyclopedia of Science Fiction

    final thoughts ...

    ... for this page, at least ...

    an excerpt from The Practice Effect

    Sooee Generis: 1

    The lecture was really boring.
              At the front of the dimly lit conference room, the portly, gray-haired director of the Sahara Institute of Technology paced back and forth — staring at the ceiling with his hands clasped behind his back — while he pontificated ponderously on a subject he clearly barely understood.
              At least that's how Dennis Nuel saw it, suffering in silence in one of the back rows.
              Once upon a time, Marcel Flaster might have been one of the shining lights of physics. But that had been long ago, before any of the younger scientists present had ever considered careers in reality physics. Dennis wondered what could have ever have converted a once-talented mind into a boring, tendentious administrator. He swore he would jump off of Mt. Feynman before it ever happened to him.
              The sonorous voice droned on.
              "And so we see, people, that by using zievatronics alternate realities appear to be almost within our reach, presenting possibilities for bypassing both space and time...."
        Dennis nursed his hangover near the back of the crowded conference room, and wondered what power on Earth could have dragged him out of bed on a Monday morning to come down here and listen to Marcel Flaster expound about zievatronics.
              His eyelids drooped. He began to slump in his seat.
              "Dennis!" Gabriella Versgo elbowed him in the ribs, whispering sharply. "Will you straighten up and pay attention?"
              Dennis sat up quickly, blinking. Now he recalled what power on Earth had dragged him here.
              At seven a.m. Gabbie had kicked open the door to his room and hauled him by his ear into the shower, ignoring his howling protests and his modesty. She had kept her formidable grip on his arm until they were both planted here in the Sahara Tech conference room.
              Dennis rubbed his arm just above the elbow. One of these days, he decided, he was going to sneak into Gabbie's room and throw away all the little rubber balls the redhead liked to squeeze while she studied.
              She nudged him again. "Will you sit still? You have the attention span of a cranky otter! Do you want to find yourself exiled even farther from the zievatronics experiment?"
              As usual, Gabbie hit close to home. He shook his head silently and made an effort to be attentive.
              Dr. Flaster finished drawing a vague figure in the holo tank at the front of the seminar room. The psychophysicist put his light-pen down on the podium and unconsciously wiped his hands on his pants, though the last piece of blackboard chalk had been outlawed more than thirty years before.
              "That is a zievatron," he announced proudly.
              Dennis looked at the light-drawing unbelievingly. He whispered, "If that's a zievatron, I'm a teetotaler. Flaster's got the poles reversed, and the field's inside out!"
              Gabriella's blush almost matched the shade of her fiery hair. Her fingernails lanced into his thigh.
              Dennis winced, but managed an expression of lamblike innocence when Flaster looked up myopically. After a moment the director cleared his throat.
              "As I was saying earlier, all bodies possess centers of mass. The centroid of an object is the balance point, where all net forces can be said to come to play... where its reality can be ascribed.
              "You, my boy," he said, pointing to Dennis. "Can you tell me where your centroid is?"
              "Umm," Dennis considered foggily. He hadn't really been listening all that carefully. "I guess I must have left it at home, sir."
              Snickers came from some of the other postdocs seated around the back of the room. Gabbie's blush deepened. She sank into her seat, obviously wishing she were elsewhere.
              The Chief Scientist smiled vaguely. "Ah, Nuel, isn't it? Dr. Dennis Nuel?"
              Across the aisle, Dennis caught a glimpse of Bernard Brady grinning at his predicament. The tall, beagle-eyed young man had once been his chief rival until managing to have Dennis completely removed from the activity in the main zievatronics laboratory. Brady gave Dennis a smile of pure spite.
              Dennis shrugged. After what had happened in the past few months, he felt he had little left to lose.
              "Uh, yessir. Dr. Flaster. It's kind of you to remember me. I used to be assistant director of Lab One, you might recall."
              Gabriella continued her descent into the upholstery, trying very much to took as if she had never seen Dennis before in her life.
              Flaster nodded. "Ah, yes. Now I recollect. As a matter of fact, your name has crossed my desk very recently."
              Bernard Brady's face lit up. Clearly, nothing would please Brady more than if Dennis were sent on a far-away sample-collecting mission... say, to Greenland or Mars. So long as he remained, Dennis presented a threat to Brady's relentless drive to curry favor and climb the bureaucratic ladder. Also, without really wishing to be, Dennis seemed to be an obstacle to Brady's romantic ambitions for Gabriella.
              "In any event. Dr. Nuel," Flaster continued, "you certainly cannot have 'left' your centroid anywhere. I believe if you check you'll find it somewhere near your navel."
              Dennis looked down at his belt buckle, then beamed back at the Director.
        Why, so it is! You can be sure I'll keep better track of it in the future!
              "It's disappointing to learn," Flaster said, affecting a hearty tone, "that someone so adept with a makeshift sling knows so little about center of mass!"
              He was clearly referring to the incident a week ago, at the staff formal dance, when a nasty little flying creature had come streaking in through a window, terrorizing the crowd around the punch bowl. Dennis had removed his cummerbund, folded it into a sling, and flung a shot glass to bring down the batlike creature before it could hurt someone seriously with its razor-sharp beak.
              The improvisation had made him an instant hero among the postdocs and techs and got Gabbie started on her present campaign to "save his career." But at the time all he had really wanted was to get a closer look at the little creature. The brief glimpse be caught had set his mind spinning with possibilities.
              Most of those present at the dance had assumed that it was an escaped experiment from the Gene-craft Center, at the opposite end of the Institute. But Dennis had other ideas.
              One look had told him that the thing had clearly not come from Earth!
              Taciturn men from Security had quickly arrived and crated the stunned animal away. Still, Dennis was certain it had come from Lab One... his old lab, where the main zievatron was kept... now off limits to everyone but Flaster's hand-picked cronies.
              "Well, Dr. Flaster," Dennis ventured, "since you bring up the subject, I'm sure we're all interested in the centroid of that vicious little varmint that buzzed the party. Can you tell us what it was, at last?"
              Suddenly it was very quiet in the conference room. It was an unconventional thing to do, challenging the Chief Scientist in front of everybody. But Dennis didn't care anymore. Without any apparent reason the man had already reassigned him away from his life's work. What more could Flaster do to him?
              Flaster regarded Dennis expressionlessly. Finally he nodded. "Come to my office an hour after the seminar, Dr. Nuel. I promise I will answer all of your questions then."
              Dennis blinked, surprised. Did the fellow really mean it?
              He nodded. Indicating he would be there, and Flaster turned back to his holosketch.
              "As I was saying," Flaster resumed, "a psychosomatic reality anomaly has its start when we surround a center of mass by a field of improbability which..."
              When attention had shifted fully away from them, Gabriella whispered once more in Dennis's ear. "Now you've done it!" she said.
              "Hmm? Done what?" He looked back at her innocently.
              "As if you don't know!" she bit. "He's going to send you to the Qattara Depression to count sand grains! You watch!"

              On those rare occasions when he remembered to correct his posture, Dennis Nuel stood a little above average in height. He dressed casually... some might say sloppily. His hair was slightly too long for the current style — more out of a vague obstinacy than out of any real conviction.
              Dennis's face sometimes took on that dreamy expression often associated either with genius or an inspired aptitude for practical jokes. In reality he was just a little too lazy to qualify for the former, and just a bit too goodhearted for the latter. He had curly brown hair and brown eyes that were right now just a little reddened from a poker game that had gone on too late the night before.
              After the lecture, as the crowd of sleepy junior scientists dispersed to find secret corners in which to nap, Dennis paused by the department bulletin board, hoping to see an advertisement for another research center working in zievatronics.
              Of course, there weren't any. Sahara Tech was the only place doing really advanced work with the ziev effect. Dennis should know. He had been responsible for many of those advances. Until six months ago.
              As the conference room emptied, Dennis saw Gabriella leave, chattering with her hand on Bernard Brady's arm. Brady looked pumped up, as if he had just conquered Mt. Everest. Clearly he was crazy in love.
              Dennis wished the fellow luck. It would be nice to have Gabriella's attentions focused elsewhere for a while. Gabbie was a competent scientist in her own right, of course. But she was just a bit too tenacious for Dennis to relax with.
              He looked at his watch. It was time to go see what Flaster wanted. Dennis brought his shoulders back. He had decided he wouldn't put up with any further put-offs. Flaster was going to answer some questions, or Dennis was going to quit!

    Sooee Generis: 2

    "Ah, Nuel! Come in!"
              Silver-haired and slightly paunched, Marcel Flaster rose from behind the gleamingly empty expanse of his desk. "Take a seat, my boy. Have a cigar? They're fresh from New Havana, on Venus." He motioned Dennis to a plush chair next to a floor-to-ceiling lavalamp.
              "So tell me, young man, how is it going with that artificial-intelligence project you've been working on?"
              Dennis had spent the past six months directing a small AI program mandated by an unbreakable old endowment — even though it had been proved back in 2024 that true artificial intelligence was a dead end field.
              He still had no idea why Flaster had asked him here. He didn't want to be gratuitously impolite, so he reported on the recent, modest advances his small group had made.
              "Well, there's been some progress. Recently we've developed a new, high-quality mimicry program. In telephone tests it conversed with randomly selected individuals for an average of six point three minutes before they suspect that they're actually talking to a machine. Rich Schwall and I think..."
              "Six and a half minutes!" Plaster interrupted. "Well, you've certainly broken the old record, by over a minute, I believe! I'm impressed!"
              Then Flaster smiled condescendingly. "But honestly, Nuel, you don't think I assigned a young scientist of your obvious talents to a project with so little long-range potential for no reason, do you?"
              Dennis shook his head. He had long ago concluded that the Chief Scientist had shoved him into a corner of Sahara Tech in order to put his own cronies into the zievatronics lab.
              Until the death of Dennis's old mentor, Dr. Guinasso, Dennis had been at the very center of the exciting field of reality analysis.
              Then, within weeks of the tragedy, Flaster had moved his own people in and Guinasso's inexorably out. Thinking about it still made Dennis bitter. He had felt sure they were just about to make tremendous discoveries when he was exiled from the work he loved.
              "I couldn't really guess why you transferred me," Dennis said. "Umm, could it be you were grooming me for better things?"
              Oblivious to the sarcasm, Flaster grinned. "Exactly, my boy! You do show remarkable insight. Tell me, Nuel. Now that you've had experience running a small department, how would you like to take charge of the zievatronics project here at Sahara Tech?"
              Dennis blinked, taken completely by surprise.
              "Uh," he said concisely.
              Flaster got up and went to an intricate espresso urn on a sideboard. He poured two demitasses of thick Atlas Mountains coffee and offered one to Dennis. Dennis took the small cup numbly. He barely tasted the heavy, sweet brew.
              Flaster returned to his desk and sipped delicately from his demitasse.
              "Now, you didn't think we'd let our best expert on the ziev effect molder in a backwater forever, did you? Of course not! I was planning to move you back into Lab One in a matter of weeks, anyway. And now that the subministry position has opened up..."
              "The what?"
              "The subministry! Mediterranea's government has shifted again, and my old friend Boona Calumny is slotted for the Minister of Science portfolio. So when he called me just the other day to ask for help..." Flaster spread his hands as if to say the rest was obvious.
              Dennis couldn't believe he was hearing this. He had been certain the older man disliked him. What in the world would motivate him to turn to Dennis when it came to choosing a replacement?
              Dennis wondered if his dislike for Flaster had blinded him to some nobler side of the man.
              "I take it you're interested?"
              Dennis nodded. He didn't care what Flaster's motives were, so long as he could get his hands on the zievatron again.
              "Excellent!" Flaster raised his cup again. "Of course, there is one small detail to overcome first — only a minor matter, really. Just the sort of thing that would show the lab your leadership ability and guarantee your universal acceptance by all."
              "Ah," Dennis said. I knew it! Here it comes! The catch!
              Flaster reached under the desk and pulled out a glass box.
              Within it was a furry-winged, razor-toothed monstrosity, rigid and lifeless.
              "After you helped us recapture it last Saturday night, I decided it was more trouble than it was worth. I handed it over to our taxidermist...."
              Dennis tried to breathe normally, The small black eyes stared back at him glassily. Right now they seemed filled less with malevolence than with deep mystery.
              "You wanted to know more about this thing," Flaster said. "As my heir apparent, you have a right to find out."
              "The others think it's from the Gene-craft Center," Dennis said.
              Flaster chuckled. "But you knew better all along, right? The lifemakers aren't good enough at their new art to make anything quite so unique," he said with savor. "So very savage.
              "No. As you guessed, our little friend here is not from the genetics labs, nor from anywhere in the solar system, for that matter. It came from Lab One — from one of the anomaly worlds we've latched onto with the zievatron."
              Dennis stood. "You got it to work! You latched onto something better than vacuum, or purple mist!"
              His mind whirled. "It breathed Earth air! It gobbled down a dozen canapes, along with a corner of Brian Yen's ear, and kept going! The thing's biochemistry must be..."
              "Is... it is almost precisely Terran." Flaster nodded.
              Dennis shook his head. He sat down heavily. "When did you find this place?"
              "We found it during a zievatronics anomaly search three weeks ago. After five months of failure, I'll freely admit that we finally achieved success only after returning to the search routine you first designed, Nuel."
              Flaster took off his glasses and wiped them with a silk handkerchief. "Your routines worked almost at once. And turned up the most amazingly Earthlike world. The biologists are ecstatic, to say the least."
              Dennis stared at the dead creature in the glass. A whole world! We did it!
              Dr. Guinasso's dream had come true. The zievatron was the key to the stars! Dennis's personal resentment had disappeared. He was genuinely thrilled by Flaster's accomplishment.
               The Director rose and returned to the coffee urn for a refill. "There's only one problem," he said nonchalantly, his back to the younger man.
              Dennis looked up, his thoughts still spinning. "Sir? A problem?"
              "Well, yes," Flaster turned around, stirring his coffee. "Actually, it has to do with the zievatron itself."
              Dennis frowned.
              "What about the zievatron?"
              Flaster raised his demitasse with two fingers. "Well," he sighed between sips. "It seems we can't get the darned thing to work anymore."

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