There was an actual bank, of sorts, where Arlington became Somerville. It had once been a savings and loan establishment. Now there was a card in the cracked window that said FAMILY BANK · DEPOSITS PROTECTED · LOANS MADE TO PERMENT RESADENTS. The best spelling he’d seen so far.

The place had a big walk-in safe, standing open, flanked by young men armed with assault rifles. It probably had a worthless electronic lock.

Even with the big window and open door, it was kind of gloomy inside. There was a man wearing a shabby coat and tie sitting at a broad table in the middle of the lobby, a tall filing cabinet behind him. In front of him, bowls of coins and a sawed-off shotgun.

“Good afternoon,” he said. “I don’t know you.”

“Just passing through. I wondered what this was worth.” He took the hundred-dollar bill from his shirt pocket and unfolded it and laid it in front of the man.

The banker picked up a white plastic thing that resembled Mose’s fishing reel, but when he cranked the handle it made an intense spot of white light. He scrutinized the bill with a magnifying glass, then held the light behind it, looking at the structure of imbedded wires. He rubbed the president’s face with his thumb and it faintly said “hundred.”

“It’s well preserved,” he said. “Where’d you find it?”

“In a trunk,” he said, true enough. “What’s it worth?”

He rubbed his chin. “I could give you fifty for it.”

“Thanks,” Matt said, reaching for the bill. “I may be back.”

The banker snatched it away. “Just a second.” He cranked the light up again, and studied both sides, then sniffed it. “Twenty seventy-four . . . maybe I could give you seventy. Seventy-five if you have more.”

“That’s the only one I’ve got. I’ll take seventy-five for it.”

The man pretended to consider it. “All right.” He pulled out a fat wallet and extracted three faintly glowing twenties, then scooped three heavy five-dollar coins from a bowl. Matt put the coins in his pocket and held up the bills to the dim light. He couldn’t identify the portrait. They were soft and worn but looked like real currency.

“Come by if you find another one of those.”

“I might.” First see what he could get in Boston proper.

When he got to Porter Square he had to make a decision: keep going down Mass Ave where it turned, or continue straight on through what used to be a bad neighborhood. On a bike, from here it was a ten-minute cruise to campus. He’d never walked it, but it was probably half the distance of going down Mass Ave through Harvard Square.

Carrying the bag and toolbox was wearing him down, and the neighborhood didn’t look that foreboding in the afternoon light.

Besides, he did have a gun, though the idea of using it gave him a sudden thrill of dread. His total experience with firearms was a forbidden friend’s BB gun at the age of twelve, and he hadn’t even been able to hit the target.

Well, he didn’t intend to shoot it. But it could be a powerful psychological weapon. Unless his adversary had one as well.

Mose hadn’t ever seen a pistol, yet the idea of it was obviously potent and frightening. Matt felt its considerable weight and strode on down through the slums.

Actually, once he was in the neighborhood, it didn’t seem any more run-down than what he’d just come from. No street merchants and fewer people. No pets, he suddenly realized; there ought to be dogs barking and cats lazing in the sun. An unaffordable luxury, he supposed, when you couldn’t just pop down to the grocery for pet food.

Every now and then a bicycle would rattle past, and twice mule-drawn carts. The mules had to eat; their existence implied a certain level of civilization, organization, since there were no pastures around where they could freely forage.

Of course they might not be completely natural. The anomaly of the bioengineered Christian fish was no anomaly, actually; this culture was going to be a mixture of high technology and low. He had to keep his eyes and mind open.

Inman Square was reassuring, a couple of blocks of vendors’ tables and a small crowd milling. There was a table full of books, but they were all Bibles, hymnals, and tracts. He bought a small New Testament, well thumbed and full of underlined passages, for nine dollars. Protective coloration and research. It would be smart to start learning something about Jesus.

A tea shop was open, so he sat down there to rest and watch the crowd. The teas on the menu were mostly herbal, probably homegrown or gathered locally. A cup of “Chinese tea” went for twenty bucks, the same as “real coffey.” He settled for a fifty-cent spearmint infusion.

So imports were expensive, even next to a huge port. It occurred to him that he hadn’t heard or seen a single airplane. At three in the afternoon the sky was a deep, unbroken blue. Had he ever seen a Boston sky without haze?

Nobody in the marketplace was wearing new-looking clothes. Maybe people didn’t dress up for going to the market. Maybe there weren’tany new clothes, or they were only for special occasions. Most of the women were dressed modestly, like Ruth, though some teenaged girls wore jeans or short skirts, startlingly seductive. That might be cultural; a sixteen-year-old was by definition a child, and so couldn’t be an object of desire.

Other men didn’t stare when they walked by. It would be prudent to follow that example.

He still had more than a mile to go, and he wanted to get to MIT well before offices closed. So rather than tarry for a second cup, he shouldered the bag and continued down the street. Where he saw a sign that stopped him in his tracks:

MASS. INST. OF THEOSOPHY, ONE MILE. It was over the MIT dome logo. What was theosophy? Had it existed in his time? He needed to Google.

“You need help, mister?” It was one of the gorgeous teenaged girls. He realized he was standing staring at the sign, and probably looked lost.

“What . . . uh, what’s theosophy?”

“It’s science,” she said with careful emphasis. “The science of God. Are you a pilgrim?”

“No, I guess not. Just a traveler.”

She opened her mouth to say something, then just nodded. “Good journey, then. God b’with you.” She bounced away, running to catch up with another girl.

The science of God. He’d better study that book.

Even more than that, he needed a history book. Something huge had happened. How long ago? Was it one thing, like a cataclysm, or was it a slow evolution?

The Massachusetts Institute of Theosophy? What did they do there? He would never fit in. Matthew Fuller, professor of atheism. You will be amused by his quaint theosophy.

Or maybe they still did do science and engineering, but had to make it appear closer to religion, for some social reason. Like this Second Coming.

Soon he was walking among tall buildings that in his day had been more or less independent research establishments associated with the Institute. People like Professor Marsh would often split their time, teaching at MIT a few days a week while maintaining lab space down the street at Biotech or Allied Chemical. MIT’s charter had forbidden some kinds of work, like weapons research, but it couldn’t control what happened slightly off campus.

Those tall, proud buildings were tenements now, with clothes flapping on lines, kids playing in the dignified court-yards. Scrawny vegetable gardens where there used to be elaborate flower beds and fantastic topiary.

But the fact that people could grow vegetables out in the open and not have their crops pilfered demonstrated a reassuring degree of social order. Along with the absence of actual starvation.

No telling where MIT’s administration would be nowadays. Building One would have enough natural light, assuming no electricity, so maybe it would still be there. He angled across campus toward the Infinite Corridor.