"Huh?"

"He couldn't. You had done something wrong... but the fact itself showed that you were ignorant. Fritz had momentarily forgotten, then he remembered and his anger disappeared. The People do not permit themselves to be angry with a child; instead they set him back on the proper path... until he follows your complex customs as automatically as Fritz does."

"Uh, I think I see." Thorby sighed. "But it isn't easy."

"Because you weren't born to it. But you'll learn and it will be no more effort than breathing -- and as useful. Customs tell a man who he is, where he belongs, what he must do. Better illogical customs than none; men cannot live together without them. From an anthropologist's view, 'justice' is a search for workable customs."

"My father -- my other father, I mean; Baslim the Cripple -- used to say the way to find justice is to deal fairly with other people and not worry about how they deal with you."

"Doesn't that fit what I said?"

"Uh, I guess so."

"I think Baslim the Cripple would regard the People as just." She patted his shoulder. "Never mind, Thorby. Do your best and one day you'll marry one of those nice girls. You'll be happy."

The prophecy did not cheer Thorby.

By the time Sisu approached Losian Thorby had a battle station worthy of a man. His first assignment had been to assist in the central dressing station, an unnecessary job. But his background in mathematics got him promoted.

He had been attending the ship's school. Baslim had given him a broad education, but this fact did not stand out to his instructors, since most of what they regarded as necessary -- the Finnish language as they spoke it, the history of the People and of Sisu, trading customs, business practices, and export and import laws of many planets, hydroponics and ship's economy, ship safety and damage control -- were subjects that Baslim had not even touched; he had emphasized languages, science, mathematics, galactography and history. The new subjects Thorby gobbled with a speed possible only to one renshawed by Baslim's strenuous methods. The Traders needed applied mathematics -- bookkeeping and accounting, astrogation, nucleonics for a hydrogen-fusion-powered n-ship. Thorby splashed through the first, the second was hardly more difficult, but as for the third, the ship's schoolmaster was astounded that this ex-fraki had already studied multi-dimensional geometries.

So he reported to the Captain that they had a mathematical genius aboard.

This was not true. But it got Thorby reassigned to the starboard fire-control computer.

The greatest hazard to trading ships is in the first and last legs of each jump, when a ship is below speed-of-light. It is theoretically possible to detect and intercept a ship going many times speed-of-light, when it is irrational to the four-dimensional space of the senses; in practice it is about as easy as hitting a particular raindrop with a bow and arrow during a storm at midnight. But it is feasible to hunt down a ship moving below speed-of-light if the attacker is fast and the victim is a big lumbering freighter.

The Sisu had acceleration of one hundred standard gravities and used it all to cut down the hazard time. But a ship which speeds up by a kilometer per second each second will take three and one half standard days to reach speed-of-light.

Half a week is a long, nervous time to wait. Doubling acceleration would have cut danger time by half and made the Sisu as agile as a raider -- but it would have meant a hydrogen-fission chamber eight times as big with parallel increase in radiation shielding, auxiliary equipment, and paramagnetic capsule to contain the hydrogen reaction; the added mass would eliminate cargo capacity. Traders are working people; even if there were no parasites preying on them they could not afford to burn their profits in the inexorable workings of an exponential law of multi-dimensional physics. So the Sisu had the best legs she could afford-but not long enough to outrun a ship unburdened by cargo.

Nor could Sisu maneuver easily. She had to go precisely in the right direction when she entered the trackless night of n-space, else when she came out she would be too far from market; such a mistake could turn the ledger from black to red. Still more hampering, her skipper had to be prepared to cut power entirely, or risk having his in-ship artificial gravity field destroyed -- and thereby make strawberry jam of the Family as soft bodies were suddenly exposed to one hundred gravities.

This is why a captain gets stomach ulcers; it isn't dickering for cargoes, figuring discounts and commissions, and trying to guess what goods will show the best return. It's not long jumps through the black -- that is when he can relax and dandle babies. It is starting and ending a jump that kills him off, the long aching hours when he may have to make a split-second decision involving the lives -- or freedom -- of his family.

If raiders wished to destroy merchant ships, Sisu and her sisters would not stand a chance. But the raider wants loot and slaves; it gains nothing simply to blast a ship.

Merchantmen are limited by no qualms; an attacking ship's destruction is the ideal outcome. Atomic target-seekers are dreadfully expensive, and using them up is rough on profit-and-loss -- but there is no holding back if the computer says the target can be reached -- whereas a raider will use destruction weapons only to save himself. His tactic is to blind the trader, burn out her instruments so that he can get close enough to paralyze everyone aboard -- or, failing that, kill without destroying ship and cargo.

The trader runs if she can, fights if she must. But when she fights, she fights to kill.

Whenever Sisu was below speed-of-light, she listened with artificial senses to every disturbance in multi-space, the whisper of n-space communication or the "white" roar of a ship boosting at many gravities. Data poured into the ship's astrogational analog of space and the questions were: Where is this other ship? What is its course? speed? acceleration? Can it catch us before we reach n-space?

If the answers were threatening, digested data channeled into port and starboard fire-control computers and Sisu braced herself to fight. Ordnancemen armed A-bomb target seekers, caressed their sleek sides and muttered charms; the Chief Engineer unlocked the suicide switch which could let the power plant become a hydrogen bomb of monstrous size and prayed that, in final extremity, he would have the courage to deliver his people into the shelter of death; the Captain sounded the clangor calling the ship from watch-and-watch to General Quarters. Cooks switched off fires; auxiliary engineers closed down air circulation; farmers said good-by to their green growing things and hurried to fighting stations; mothers with babies mustered, then strapped down and held those babies tightly.

Then the waiting started.

But not for Thorby -- not for those assigned to fire-control computers. Sweating into their straps, for the next minutes or hours the life of Sisu is in their hands. The fire-control computer machines, chewing with millisecond meditation data from the analog, decide whether or not torpedoes can reach the target, then offer four answers: ballistic "possible" or "impossible" for projected condition, yes or no for condition changed by one ship, or the other, or both, through cutting power. These answers automatic circuits could handle alone, but machines do not think. Half of each computer is designed to allow the operator to ask what the situation might be in the far future of five minutes or so from now if variables change... and whether the target might be reached under such changes.