"Because you're an Earthman. Some Earth-people consider it a term of derision and resent it when a Lunarite uses it."

"You mean when a Lunie uses it?"

Selene flushed. She said, "Yes. That's about it."

"Well, then, let's neither of us cry out at words. Go ahead, you were telling me about your job."

"On my job, there are these Earthies whom I have to keep from killing themselves and whom I have to take here and there and give little speeches to and make sure they eat and drink and walk by the book. They see their little pet sights and do their little pet things, and I have to be terribly polite and motherly."

"Awful," said the Earthman.

"But you and I can do as we please, I hope, and you are willing to take your chances and I don't have to watch what I say."

"I told you that you're perfectly welcome to call me Earthie."

"All right, then. I'll have a busman's holiday. What would you like to do?"

"That's an easy one to answer. I want to see the proton synchrotron."

"Not that Maybe Barren can arrange it after you see him."

"Well, if I can't see the synchrotron, I don't know what else there is to see. I know the radio telescope is on the other side and I don't suppose there's any novelty in it, anyway. . . . You tell me. What doesn't the average tourist get to see?"

"A number of things. There are the algae rooms - not the antiseptic processing plants, which you've seen - but the farms themselves. However, the smell is pretty strong there and I don't suppose an Earthie - Earthman - would find it particularly appetizing. Earth - men have trouble with the food as it is."

"Does that surprise you? Have you ever tasted Earth-food?"

"Not really. I probably wouldn't like it, though. It all depends on what you're used to."

"I suppose so," said the Earthman, sighing. "If you ate a real steak, you'd probably gag at the fat and fiber."

"We could go to the outskirts where the new corridors are being driven into bedrock, but you'll have to wear special protective garments. There are the factories - "

"You make the choice, Selene."

"I will, if you will tell me something honestly."

"I can't promise without hearing the question."

"I said that Earthies that didn't like Earthies tended to stay on the Moon. You didn't correct me. Do you intend to stay on the Moon?"

The Earthman stared at the toes of his clumsy boots. He said, "Selene, I had trouble getting a visa to the Moon. They said I might be too old for the trip and that if I stayed any length of time I might find it impossible to return to Earth. So I told them I planned to stay on the Moon permanently."

"You weren't lying?

"I wasn't sure at the time. But I think I'll stay here now."

"I should have thought that they would have been less willing than ever to let you go under those conditions."

"Why?"

"Generally, the Earth authorities don't like to send physicists to the Moon on a permanent basis."

The Earthman's lips twitched. "In that respect, I had no trouble."

"Well, then, if you're going to be one of us, I think you ought to visit the gymnasium. Earthies often want to but we don't encourage them as a general rule - though it's not forbidden outright Immigrants are a different thing."

"Why?"

"Well, for one thing, we exercise in the nude or near-nude. Why not?" She sounded aggrieved, as though weary of repeating a defensive position. "The temperature is controlled; the environment is clean. It's just that where people from Earth are expected to be, nudity becomes unsettling. Some Earthies are shocked; some are titillated; and some are both. Well, we're not going to dress in the gymnasium for their sake, and we're not going to cope with them, either; so we keep them out"

"But immigrants?"

"They have to get used to it. In the end, they'll be discarding clothes, too. And they'll need the gymnasium even more than the native Lunarites do."

'Til be honest with you, Selene. If I encounter female nudity, I'll find it titillating, too. I'm not quite so old that I won't"

"Well, titillate, then," she said, indifferently, "but to yourself. Agreed?"

"Do we have to get undressed too?" He looked at her with amused interest.

"As spectators? No. We could, but we don't have to. You would feel uncomfortable if you did this early in the game and you wouldn't be a particularly inspiring sight to the rest of us - "

"You are frank!"

"Do you think it would be? Be honest And as for myself, I have no wish to put you under a special strain in your private titillation. So we might both just as well stay clothed."

"Will there be any objection? I mean to my being there as an Earthie of uninspirational appearance?"

"Not if I'm with you."

"Very well, then, Selene. Is it far away?"

"We are there. Just through here."

"Ah, then, you were planning to come here all the time."

"I thought it might be interesting."

"Why?"

Selene smiled suddenly. "I just thought."

The Earthman shook his head. "I'm beginning to think you never just think. Let me guess. If I'm to stay on the Moon, I will need to exercise now and then in order to keep muscles, bones, and all my organs, perhaps, in condition."

"Quite true. So do all of us, immigrants from Earth in particular. The day will come when the gymnasium will be a daily grind for you."

They stepped through a door and the Earthman stared in astonishment. "This is the first place I've seen that looks like Earth."

"In what way?"

"Why it's big. I didn't imagine you would have such big rooms on the Moon. Desks, office machinery, women at the desks - "

"Bare-breasted women," said Selene, gravely.

"That part isn't Earthlike, I admit."

"We've got a hold-chute, too, and an elevator for Earthies. There are many levels . . . But wait."

She approached a woman at one of the nearer desks, talking in a rapid, low voice while the Earthman stared at everything with amiable curiosity.

Selene returned. "No trouble. And it turns out we're going to have a melee. A rather good one; I know the teams."

"This place is very impressive. Really."

"If you still mean its size, it's not nearly big enough. We have three gymnasiums. This is the largest."

"I'm somehow pleased that in the Spartan surroundings of the Moon, you can afford to waste so much room on frivolity."

"Frivolity!" Selene sounded offended. "Why do you think this is frivolity?"

"Melees? Some sort of game?"

"You might call it a game. On Earth you can do such things for sports; ten men doing, ten thousand watching. It's not so on the Moon; what's frivolous for you is necessary for us, . . . This way; we'll take the elevator, which means a little waiting perhaps."

"Didn't mean to get you angry."

"I'm not really angry but you must be reasonable. You Earthmen have been adapted to Earth-gravity for all the three hundred million years since life crawled onto dry land. Even if you don't exercise, you get by. We've had no time at all to adapt to Moon-gravity."

"You look different enough."

"If you're born and reared under Moon-gravity, your bones and muscles are, naturally, slimmer and less massive than an Earthie's would be, but that's superficial. There isn't a bodily function we possess, however subtle - digestion, rates of hormonal secretions - that isn't maladjusted to gravity and that doesn't require a deliberate regimen of exercise. If we can arrange exercise in the form of fun and games that does not make it frivolity . . . Here's the elevator."

The Earthman hung back in momentary alarm, but Selene, said, with residual impatience, as though still seething over the necessity of defense. "I suppose you're going to tell me it looks like a wickerwork basket. Every Earthman who uses it says so. With Moon-gravity, it doesn't have to be any more substantial."

The elevator moved downward slowly. They were the only ones on board.

The Earthman said, "I suspect this isn't much used."

Selene smiled again. "You're right. The hold-chute is much more popular, and much more fun."

"What is it?"

"Exactly what the name implies . . . Here we are. We only had to drop two levels . . . It's just a vertical tube you can drop through, with handholds. We don't encourage Earthies to use it."

"Too risky?"

"Not in itself. You can climb down as though it were a ladder. However, there are always youngsters swinging down at considerable speed and Earthies don't know how to keep out of the way. Collisions are always discomforting. But you'll get to use it in time. . . . In fact, what you'll see now is a kind of large hold-chute designed for recklessness." ^

She led him to a circular railing around which a number of individuals were leaning and talking. All were more or less in the nude. Sandals were common and usually a hip-purse was slung over one shoulder. Some wore briefs. One was scooping a greenish-mash out of a container and was eating it.

The Earthman wrinkled his nose slightly as he passed that one. He said, "The dental problem must be severe on the Moon."

"It isn't good," Selene agreed. "Ifwe ever get the chance, we'll select for an edentate jaw."

"Toothlessness?"

"Maybe not entirely. We might keep the incisors and canines for cosmetic reasons and for occasionally useful tasks. They're easily cleaned, too. But why should we want useless molars? It's just a hangover from an Earthie past."

"Are you making any progress in that direction?"

"No," she said, stiffly. "Genetic engineering is illegal. Earth insists."

She was leaning over the railing. "They call this the Moon's playground," she said.

The Earthman looked down. It was a large cylindrical opening with pink smooth walls to which metal bars were attached in what seemed a random configuration. Here and there, a bar stretched across a portion of the cylinder, sometimes across its entire width. It was perhaps four or five hundred feet deep and about fifty feet across.

No one seemed to be paying particular attention either to the playground or to the Earthman. Some had looked at him indifferently as he passed, seeming to weigh his clothed state, his facial appearance, and then had turned away. Some made a casual hand gesture to Selene's direction before turning away, but all turned away. The no-interest signal, however subdued, could not have been more blatant.

The Earthman turned to the cylindrical opening. There were slim figures at the bottom, foreshortened because they were seen from above. Some wore wisps of clothing in red, some in blue. Two teams, he decided. Clearly the wisps served protective functions, since all wore gloves and sandals, protective bands about knees and elbows. Some wore brief bands about the hips, some about the chests.

"Oh," he muttered. "Men and women."

Selene said, "Right! The sexes compete equally but the idea is to prevent the uncontrolled swinging of parts that might hamper the guided fall. There's a sexual difference there which also involves vulnerability to pain. It's not modesty."

The Earthman said, "I think I've read of this."

"You may have," said Selene, indifferently. "Not much seems to get out. Not that we have any objection, but the Terrestrial government prefers to keep news of the Moon to a minimum."

"Why, Selene?"

"You're an Earthman. You tell me. . . . Our theory here on the Moon is that we embarrass the Earth. Or at least

the Earth government."

On either side of the cylinder now, two individuals were rising rapidly and the patter of light drumbeats was heard in the background. At first, the climbers seemed to be going up a ladder, rung by rung, but their speed increased and by the time they were halfway up, they were striking each hold as they passed, making an ostentatious slapping noise.

"Couldn't do that on Earth as gracefully," said the Earthman, admiringly. "Or at all," he amended.

"It's not just low-gravity," said Selene. "Try it, if you think so. This takes endless hours of practice."

The climbers reached the railing and swung up to a headstand. They performed a simultaneous somersault and began to fall.

"They can move quickly when they want to," said the Earthman.

"Umm," said Selene, through the patter of applause. "I suspect that when Earthmen - I mean the real Earthmen, the ones who have never even visited the Moon - think of moving around the Moon, they think of the surface and of spacesuits. That's often slow, of course. The mass, with the spacesuit added, is huge, which means high inertia and a small gravity to overcome it."

"Quite right," said the Earthman. "I've seen the classic motion pictures of the early astronauts that all school children see and the movements are like those underwater, The picture gets imprinted, even when we know better."

"You'd be surprised how fast we can move on the surface these days, spacesuit and all," said Selene. "And here, underground, without spacesuits, we can move as quickly as on Earth. The slower whip of gravity is made up for by the proper use of muscles."

"But you can move slowly, too." The Earthman was watching the acrobats. They had gone up with speed and were going down with deliberate slowness. They-were floating, slapping the handholds to delay the drop rather than, as before, to accelerate the rise. They reached the ground and two others replaced them. And then two more.

And then two more. From each team alternately, pairs competed in virtuosity.

Each pair went up in unison; each pair rose and fell in a more complicated pattern. One pair kicked off simultaneously to cross the tube in a low parabola, convex upward, each reaching the handhold the other had abandoned, and somehow skimming past each other in mid-air without touching. That evoked louder applause.

The Earthman said, "I suspect I lack the experience to appreciate the finer points of skill. Are these all native Lunarites?"

"They have to be," said Selene. "The gymnasium is open to all Lunar citizens and some immigrants are fairly good, considering. For this kind of virtuosity, however, you must depend on babies that are conceived and born here. They have the proper physical adaptation, at least more than native Earthmen have, and they get the proper childhood training. Most of these performers are under eighteen."

"I imagine it's dangerous, even at Moon-gravity levels."

"Broken bones aren't very uncommon. I don't think there's been an actual death, but there's been at least one case of broken spine and paralysis. That was a terrible accident; I was actually watching -  Oh, wait now; we're going to have the ad libs now."

"The what?"

"Till now, we've had set pieces. The climbs were according to a fixed pattern."

The percussion beat seemed softer as one climber rose and suddenly launched into mid-air. He caught a transverse bar one-handed, circling it once vertically, and let

go-

The Earthman watched closely. He said, "Amazing. He gets around those bars exactly like a gibbon."

"A what?" asked Selene.

"A gibbon. A kind of ape; in fact, the only ape still existing in the wild. They - " He looked at Selene's expression and said, "I don't mean it as an insult, Selene; they are graceful creatures."

Selene said, frowning, "I've seen pictures of apes."

"You probably haven't seen gibbons, in motion. . . . I dare say that Earthies might call Lunarites 'gibbons* and mean it insultingly, about on the level of what you mean by 'Earthie.' But I don't mean it so."

He leaned both elbows on the railing and watched the movements. It was like dancing in the air. He said, "How do you treat Earth-immigrants here on the Moon, Selene? J mean immigrants who mean to stay here life-long. Since they lack true Lunarite abilities - "

"That makes no difference. Immies are citizens. There's no discrimination; no legal discrimination."

"What does that mean? No legal discrimination?"

"Well, you said it yourself. There are some things they can't do. There are differences. Their medical problems are different and they've usually had a worse medical history. If they come in middle age, they look - old."

The Earthman looked away, embarrassed. "Can they intermarry? I mean, immigrants and Lunarites."

"Certainly. That is, they can interbreed."

"Yes, that's what I meant."

"Of course. No reason why an immigrant can't have some worthwhile genes. Heavens, my father was an immie, though I'm second-generation Lunarite on my mother's side."

"I suppose your father must have come when he was1 quite - Oh, good Lord - " He froze at the railing, then drew a shuddering sigh. "I thought he was going to miss that bar."

"Not a chance," said Selene. "That's Marco Fore. He likes to do that, reach out at the last moment. Actually, it's bad form to do that and a real champion doesn't. Still -  My father was twenty-two when he arrived."

"I suppose that's the way. Still young enough to be adaptable; no emotional complications back on Earth. From the standpoint of the Earthie male, I imagine it must be rather nice to have a sexual attachment with a - "

"Sexual attachment!" Selene's amusement seemed to cover a very real sense of shock. "You don't suppose my father had sex with my mother. If my mother heard you say that, she'd set you right in a hurry."

"But - "

"Artificial insemination was what it was for goodness sake. Sex with an Earthman?"

The Earthman looked solemn. "I thought you said there was no discrimination."

"That's not discrimination. That's a matter of physical fact. An Earthman can't handle the gravity field properly. However practiced he might be, under the stress of passion, he might revert. I wouldn't risk it. The clumsy fool might snap his arm or leg - or worse, mine. Gene mixtures are one thing; sex is quite another."

"I'm sorry . . . Isn't artificial insemination against the law?"

She was watching the gymnastics with absorption. "That's Marco Fore again. When he isn't trying to be uselessly spectacular, he really is good; and his sister is almost as good. When they work together it's really a poem of motion. Look at them now. They'll come together and circle the same bar as though they have a single body stretched across. He's a little too flamboyant at times, but you can't fault his muscular control . . . Yes, artificial insemination is against Earth's law, but it's allowed where medical reasons are involved, and, of course, that's often the case, or said to be."

AU the acrobats had now climbed to the top and were in a great circle just below the railing; all the reds on one side, the blues on the other. All arms on the side of the interior were raised and the applause was loud. Quite a crowd had now gathered at the rail.

"You ought to have some seating arrangement," said the Earthman.

"Not at all. This isn't a show. This is exercise. We don't encourage any more spectators than can stand comfortably about the railing. We're supposed to be down there, not up here."

"You mean you can do that sort of thing, Selene?"

"After a fashion, of course. Any Lunarite can. I'm not as good as they are. I haven't joined any teams -  There's going to be the melee now, the free-for-all. This is the really dangerous part. All ten are going to be in the air and each side is going to try to send members of the other side into a fall."

"A real fall."

"As real as possible."

"Are there injuries occasionally?"

"Occasionally. In theory, this sort of thing is frowned upon. That is considered frivolous, and we don't have so large a population that we can afford to incapacitate anyone without real cause. Still, the melee is popular and we can't raise the votes to outlaw it."

"Which side do you vote on, Selene?"

Selene blushed. "Oh, never mind. You watch this!"

The percussion rhythm had suddenly grown thunderous and each of the individuals in the huge well darted outward like an arrow. There was wild confusion in mid-air "but when they parted again, each ended firmly on a bar-grip. There was the tension of waiting. One launched; another followed; and the air was filled with flashing bodies again. Over and over it happened.

Selene said, "The scoring is intricate. There is a point for every launch; a point for every touch; two points for every miss inflicted; ten points for a grounding; various penalties for various kinds of fouling."

"Who keeps the score?"

"There are umpires watching who make the preliminary decisions and there are television tapes in case of appeals. Very often even the tapes can't decide."

There was a sudden excited cry when a girl in blue moved past a boy in red and slapped his flank resoundingly. The boy who received the blow had writhed away, but not successfully, and grabbing at a wall bar with improper balance struck that wall ungracefully with his knee.