The flivver descended vertically toward the green planet circling the old, orange sun.

It was a spaceship, but not the kind men had once dreamed about. The flivver was shaped like a crude bullet, blunt at one end of a fat cylinder and tapering abruptly to a point at the other. It had been slapped together out of sheet metal and insulation board, and it sold, fully equipped, for $15,730. It didn’t behave like a spaceship, either.

As it hurtled down, its speed increased with dramatic swiftness. Then, at the last instant before impact, it stopped. Just like that.

A moment later, it thumped a last few inches into the ankle-deep grass and knee-high white flowers of the meadow. It was a shock of a jar that made the sheet-metal walls boom like thunder machines. The flivver rocked unsteadily on its flat stern before it decided to stay upright.

Then all was quiet--outside.

Inside the big, central cabin, Grampa waved his pircuit irately in the air. “Now look what you made me do! Just when I had the blamed thing practically whipped, too!”

Grampa was a white-haired 90-year-old who could still go a fast round or two with a man (or woman) half his age, but he had a habit of lapsing into tantrum when he got annoyed.

“Now, Grampa,” Fred soothed, but his face was concerned. Fred, once called Young Fred, was Grampa’s only son. He was sixty and his hair had begun to gray at the temples. “That landing was pretty rough, Junior.”

Junior was Fred’s only son. Because he was thirty-five and capable of exercising adult judgment and because he had the youngest adult reflexes, he sat in the pilot’s chair, the control stick between his knees, his thumb still over the Off-On button on top. “I know it, Fred,” he said, frowning. “This world fooled me. It has a diameter less than that of Mercury and yet a gravitational pull as great as Earth.”

Grampa started to say something, but an 8-year-old boy looked up from the navigator’s table beside the big computer and said, “Well, gosh, Junior, that’s why we picked this planet. We fed all the orbital data into Abacus, and Abacus said that orbital perturbations indicated that the second planet was unusually heavy for its size. Then Fred said, ‘That looks like heavy metals’, and you said, ‘Maybe uranium--’”

“That’s enough, Four,” Junior interrupted. “Never mind what I said.”

Those were the Peppergrass men, four generations of them, looking remarkably alike, although some vital element seemed to have dwindled until Four looked pale and thin-faced and wizened.

“And, Four,” Reba said automatically, “don’t call your father ‘Junior.’ It sounds disrespectful.”

Reba was Four’s mother and Junior’s wife. On her own, she was a red-haired beauty with the loveliest figure this side of Antares. That Junior had won her was, to Grampa, the most hopeful thing he had ever noticed about the boy.

“But everybody calls Junior ‘Junior,’” Four complained. “Besides, Fred is Junior’s father and Junior calls him ‘Fred.’”

“That’s different,” Reba said.

Grampa was still waving his puzzle circuit indignantly. “See!” The pircuit was a flat box equipped with pushbuttons and thirteen slender openings in the top. One of the openings was lighted. “That landing made me push the wrong button and the dad-blasted thing beat me again.”

“Stop picking on Junior,” Joyce said sharply. She was Junior’s mother and Fred’s wife, still slim and handsome as she approached sixty, but somehow ice water had replaced the warm blood in her veins. “I’m sure he did the best he could.”

“Anybody talks about gravitational pull,” Grampa said, snorting, “deserves anything anybody could say about him. There’s no such thing, Junior. You ought to know by now that gravitation is the effect of the curving of space-time around matter. Einstein proved that two hundred years ago.”

“Go back to your games, Grampa,” Fred said impatiently. “We’ve got work to do.”

Grampa knitted his bushy, white eyebrows and petulantly pushed the last button on his pircuit. The last light went out. “You’ve got work to do, have you? Whose flivver do you think this is, anyhow?”

“It belongs to all of us,” Four said shrilly. “You gave us all a sixth share.”

“That’s right, Four,” Grampa muttered, “so I did. But whose money bought it?”

“You bought it, Grampa,” Fred said.

“That’s right! And who invented the gravity polarizer and the space flivver? Eh? Who made possible this gallivanting all over space?”

“You, Grampa,” Fred said.

“You bet! And who made one hundred million dollars out of it that the rest of you vultures are just hanging around to gobble up when I die?”

“And who spent it all trying to invent perpetual motion machines and longevity pills,” Joyce said bitterly, “and fixed it so we’d have to go searching for uranium and habitable worlds all through this deadly galaxy? You, Grampa!”

“Well, now,” Grampa protested, “I got a little put away yet. You’ll be sorry when I’m dead and gone.”

“You’re never going to die, Grampa,” Joyce said harshly. “Just before we left, you bought a hundred-year contract with that Life-Begins-At-Ninety longevity company.”

“Well, now,” said Grampa, blinking, “how’d you find out about that? Well, now!” In confusion, he turned back to the pircuit and jabbed a button. Thirteen slim lights sprang on. “I’ll get you this time!”

Four stretched and stood up. He looked curiously into the corner by the computer where Grampa’s chair stood. “You brought that pircuit from Earth, didn’t you? What’s the game?”

Grampa looked up, obviously relieved to drop his act of intense concentration. “I’ll tell you, boy. You play against the pircuit, taking turns, and you can put out one, two or three lights. The player who makes the other one turn out the last light is the winner.”

“That’s simple,” Four said without hesitation. “The winning strategy is to--”

“Don’t be a kibitzer!” Grampa snapped. “When I need help, I’ll ask for it. No dad-blamed machine is gonna outthink Grampa!” He snorted indignantly.

Four shrugged his narrow shoulders and wandered to the view screen. Within it was the green horizon, curving noticeably. Four angled the picture in toward the ship, sweeping through green, peaceful woodland and plain and blue lake until he stared down into the meadow at the flivver’s stern.

“Look!” he said suddenly. “This planet not only has flora--it has fauna.” He rushed to the air lock.

“Four!” Reba called out warningly.

“It’s all right, Reba,” Four assured her. “The air is within one per cent of Earth-normal and the bio-analyzer can find no micro-organisms viable within the Terran spectrum.”

“What about macro-organisms--” Reba began, but the boy was gone already. Reba’s face was troubled. “That boy!” she said to Junior. “Sometimes I think we’ve made a terrible mistake with him. He should have friends, play-mates. He’s more like a little old man than a boy.”

But Junior nodded meaningfully at Fred and disappeared into the chart room. Fred followed casually. Then, as the door slid shut behind him, he asked impatiently. “Well, what’s all the mystery?”

“No use bothering the others yet,” Junior said, his face puzzled. “You see, I didn’t let the flivver drop those last few inches. The polarizer quit.”

“Quit!”

“That’s not the worst. I tried to take it up again. The flivver--it won’t budge!”

The thing was a featureless blob, a two-foot sphere of raspberry gelatin, but it was alive. It rocked back and forth in front of Four. It opened a raspberry-color pseudo-mouth and said plaintively, “Fweep? Fweep?”

Joyce drew her chair farther back toward the wall, revulsion on her face. “Four! Get that nasty thing out of here!”

“You mean Fweep?” Four asked in astonishment.

“I mean that thing, whatever you call it.” Joyce fluttered her hand impatiently. “Get it out!”

Four’s eyes widened farther. “But Fweep’s my friend.”

“Nonsense!” Joyce said sharply. “Earthmen don’t make friends with aliens. And that’s nothing but a--a blob!”

“Fweep?” queried the raspberry lips. “Fweep?”

“If it’s Four’s friend,” Reba said firmly, “it can stay. If you don’t like to be around it, Grammy, you can always go to your own room.”

Joyce stood up indignantly. “Well! And don’t call me ‘Grammy!’ It makes me sound as old as that old goat over there!” She glared malignantly at Grampa. “If you’d rather have that blob than me--well!” She swept grandly out of the central cabin and into one of the private rooms that opened out from it.

“Fweep?” asked the blob.

“Sure,” Four said. “Go ahead, fweep--I mean sweep.”

Swiftly the sphere rolled across the floor. Behind it was left a narrow path of sparkling clean tile.

Grampa glanced warily at Joyce’s door to make sure it was completely closed and then cocked a white eyebrow at Reba. “Good for you, Reba!” he said admiringly. “For forty years now, I’ve wanted to do that. Never had the nerve.”

“Why, thanks, Grampa,” Reba said, surprised.

“I like you, gal. Never forget it.”

“I like you, too, Grampa. If you’d been a few years younger, Junior would have had competition!”

“You bet he would!” Grampa leaned back and cackled. Then he leaned over confidentially toward Reba and whispered, “Beats me why you ever married a jerk like Junior, anyhow.”

Reba looked thoughtfully toward the airlock door. “Maybe I saw something in him nobody else saw, the man he might become. He’s been submerged in this family too long; he’s still a child to all of you and to himself, too.” Reba smiled at Grampa brilliantly. “And maybe I thought he might grow into a man like his grandfather.”

Grampa turned red and looked quickly toward Four. The boy was staring intently at Fweep. “What you doing, Four?”

“Trying to figure out what Fweep does with the sweepings,” Four said absently. “The outer inch or two of his body gets cloudy and then slowly clears. I think I’ll try him with a bigger particle.”

“That’s the idea, Four. You’ll be a Peppergrass yet. How about building me a pircuit?”

“You get the other one figured out?”

“It was easy,” Grampa said breezily, “once you understood the principle. The player who moved second could always win if he used the right strategy. Dividing the thirteen lights into three sections of four each--”

“That’s right,” Four agreed. “I can make you a new one by cannibalizing the other pircuit, but I’ll need a few extra parts.”

Grampa pushed the wall beside his chair and a drawer slid out of it.

Inside were row after row of nipple-topped, flat-sided, flexible free-fall bottles and a battered cigar box. “Thought you’d say that,” he said, picking out the box. “Help yourself.” With the other hand, he lifted out one of the bottles and took a long drag on it. “Ahhh!” he sighed, wiped his mouth with the back of his hand, and carefully put the bottle away.

“What is that stuff you drink, Grampa?” Four asked.

“Tonic, boy. Keeps me young and frisky. Now about that pircuit--”

“Did you ever work on Niccolò Tartaglia’s puzzle about the three lovely brides, the three jealous husbands, the river and the two-passenger rowboat?”

“Yep,” Grampa said. “Too easy.”

Four thought a moment. “There’s a modern variation with three missionaries and three cannibals. Same river, same rowboat and only one of the cannibals can row. If the cannibals outnumber the missionaries--”

“Sounds good, boy,” Grampa said eagerly. “Whip it up for me.”

“Okay, Grampa.” Four looked at Fweep again. The translucent sphere had paused at Grampa’s feet.

Grampa reached down to pat it. For an instant, his hand disappeared into Fweep, and then the alien creature rolled away. This time its path seemed crooked.

Its gelatinous form jiggled. “Hic!” it said.

As if in response, the flivver vibrated. Grampa looked querulously toward the airlock. “Flivver shouldn’t shake like that. Not with the polarizer turned on.”

The airlock door swung inward. Through the oval doorway walked Fred, followed closely by Junior. They were sweat-stained and weary, scintillation counters dangling heavily from their belts.

“Any luck?” Reba asked brightly.

“Do we look it?” Junior grumbled.

“Where’s Joyce?” asked Fred. “Might as well get everybody in on this at once. Joyce!”

The door to his wife’s room opened instantly. Behind it, Joyce was regal and slim. The pose was spoiled immediately by her avid question: “Any uranium? Radium? Thorium?”

“No,” Fred said slowly, “and no other heavy metals, either. There’s a few low-grade iron deposits and that’s it.”

“Then what makes this planet so heavy?” Reba asked.

Junior shrugged helplessly and collapsed into a chair. “Your guess is as good as anybody’s.”

“Then we’ve wasted another week on a worthless rock,” Joyce complained. She turned savagely on Fred. “This was going to make us all filthy rich. We were going to find radioactives and retire to Earth like billionaires. And all we’ve done is spent a year of our lives in this cramped old flivver--and we don’t have many of them to spare!” She glared venomously at Grampa.

“We’ve still got Fweepland,” Four said solemnly.

“Fweepland?” Reba repeated.

“This planet. It’s not big, but it’s fertile and it’s harmless. As real estate, it’s worth almost as much as if it were solid uranium.”

“A good thing, too,” Junior said glumly, “because this looks like the end of our search. Short of a miracle, we’ll spend the rest of our lives right here--involuntary colonists.”

Joyce spun on him. “You’re joking!” she screeched.

“I wish I were,” Junior said. “But the polarizer won’t work. Either it’s broken or there’s something about the gravity around here that just won’t polarize.”

“It’s these ‘23 models,” Grampa put in disgustedly. “They never were any good.”

The land of the Fweep turned slowly on its axis. The orange sun set and rose again and stared down once more at the meadow where the improbable spaceship rested on its improbable stern. The sixteen Earth hours that the rotation had taken had changed nothing inside the ship, either.

Grampa looked up from his pircuit and said, “If I were you, Junior, I would take a good look at the TV repairman when we get back to Earth. If we get back to Earth,” he amended. “You can’t be Four’s father. All over the Universe, gravity is the same, and if it’s gravity, the polarizer will polarize it.”

“That’s just supposition,” Junior said stubbornly. “The fact is, it isn’t because it doesn’t. Q.E.D.”

“Maybe the polarizer is broken,” Fred suggested.

Grampa snorted. “Broken-shmoken. Nothing to break, Young Fred. Just a few coils of copper wire and they’re all right. We checked. We know the power plant is working: the lights are on, the air and water recirculation systems are going, the food resynthesizer is okay. And, anyway, the polarizer could work from the storage battery if it had to.”

“Then it goes deeper,” Junior insisted. “It goes right to the principle of polarization itself. For some reason, it doesn’t work here. Why? Before we can discover the answer to that, we’ll have to know more about polarization itself. How does it work, Grampa?”

Grampa gave him a sarcastic grin. “Now you’re curious, eh? Couldn’t be bothered with Grampa’s invention before. Oh, no! Too busy. Accept without question the blessings that the Good Lord provideth--”

“Let’s not get up on any pulpits,” Fred growled. “Come on, Grampa, what’s the theory behind polarization?”

Grampa looked at the four faces staring at him hopefully and the jeering grin turned to a smile. “Well,” he said, “at last. You know how light is polarized, eh?” The smile faded. “No, I guess you don’t.”

He cleared his throat professorially. “Well, now, in ordinary light the vibrations are perpendicular to the ray in all directions. When light is polarized by passing through crystals or by reflection or refraction at non-metallic surfaces, the paths of the vibrations are still perpendicular to the ray, but they’re in straight lines, circles or ellipses.”

The faces were still blank and unillumined.

“Gravity is similar to light,” he pressed on. “In the absence of matter, gravity is non-polarized. Matter polarizes gravity in a circle around itself. That’s how we’ve always known it until the invention of spaceships and later the polarizer. The polarizer polarizes gravity into a straight line. That makes the ship take off and continue accelerating until the polarizer is shut off or its angle is shifted.”

The faces looked at him silently. Finally Joyce could endure it no longer. “That’s just nonsense! You all know it. Grampa’s no genius. He’s just a tinkerer. One day he happened to tinker out the polarizer. He doesn’t know how it works any more than I do.”

“Now wait a minute!” Grampa protested. “That’s not fair. Maybe I didn’t figure out the theory myself, but I read everything the scientists ever wrote about it. Wanted to know myself what made the blamed thing work. What I told you is what the scientists said, near as I remember. Now me--I’m like Edison. I do it and let everybody else worry over ‘why.’”

“The only thing you ever did was the polarizer,” Joyce snapped. “And then you spent everything you got from it on those fool perpetual-motion machines and those crazy longevity schemes when any moron would know they were impossible.”

Grampa squinted at her sagely. “That’s what they said about the gravity polarizer before I invented it.”

“But you don’t really know why it works,” Junior persisted.

“Well, no,” Grampa admitted. “Actually I was just fiddling around with some coils when one of them took off. Went right through the ceiling, dragging a battery behind it. I guess it’s still going. Ought to be out near the Horsehead Nebula by now. Luckily, I remembered how I’d wound it.”

“Why won’t the ship work then, if you know so much?” Joyce demanded ironically.

“Well, now,” Grampa said in bafflement, “it rightly should, you know.”

“We’re stuck,” Reba said softly. “We might as well admit it. All we can do is set the transmitter to send out an automatic distress call--”

“Which,” Joyce interrupted, “might get picked up in a few centuries.”

“And make the best of what we’ve got,” Reba went on, unheeding. “If we look at it the right way, it’s quite a lot. A beautiful, fertile world. Earth gravity. The flivver--even if the polarizer won’t work, there’s the resynthesizer; it will keep us in food and clothes for years. By then, we should have a good-sized community built up, because out here we won’t have to stop with one child. We can have all the babies we want.”

“You know the law: one child per couple,” Joyce reminded her frigidly. “You can condemn yourself to exile from civilization if you wish. Not me.”

Junior frowned at his wife. “I believe you’re actually glad it happened.”

“I could think of worse things,” Reba said.

“I like your spunk, Reb,” Grampa muttered.

“Speaking of children,” Junior said, “where’s Four?”

“Here.” Four came through the airlock and trudged across the room, carrying a curious contraption made of tripod legs supporting a small box from which dangled a plumb bob. Behind Four, like a round, raspberry shadow, rolled Fweep.

“Fweep?” it queried hopefully.

“Not now,” said Four.

“Where’ve you been?” Reba asked anxiously. “What’ve you been doing?”

“I’ve been all over Fweepland,” Four said wearily, “trying to locate its center of gravity.”

“Well?” Fred prompted.

“It shifts.”

“That’s impossible,” said Junior.

“Not for Fweep,” Four replied.

“What do you mean by that?” Joyce suspiciously asked.

“It shifted,” Four explained patiently, “because Fweep kept following me.”

“Fweep?” Junior repeated stupidly.

“Fweep?” Fweep said eagerly.

“He’s why the flivver won’t work. What Grampa invented was a linear polarizer. Fweep is a circular polarizer. He’s what makes this planet so heavy. He’s why we can’t leave.”