Focus. Concentration.

With effort, mustering both, differences are perceived, revealing the structure of reality, so that—

A shift, a reduction in sharpness, a diffusion of awareness, the perception lost, and—

No. Force it back! Concentrate harder. Observe reality, be aware of its parts.

But the details are minute, hard to make out. Easier just to ignore them, to relax, to … fade … and…

No, no. Don’t slip away. Hold on to the details! Concentrate.

Quan Li had obtained privileged status for someone only thirty-five years old. He was not just a doctor but also a senior member of the Communist Party, and the size of his thirtieth-floor Beijing apartment reflected that.

He could list numerous letters after his name — degrees, fellowships — but the most important ones were the three that were never written down, only said, and then only by the few of his colleagues who spoke English: Li had his BTA; he’d Been To America, having studied at Johns Hopkins. When the phone in his long, narrow bedroom rang, his first thought, after glancing at the red LEDs on his clock, was that it must be some fool American calling. His US colleagues were notorious for forgetting about time zones.

He fumbled for the black handset and picked it up. “Hello?” he said in Mandarin.

“Li,” said a voice that quavered so much it made his name sound like two syllables.

“Cho?” He sat up in the wide, soft bed and reached for his glasses, sitting next to the copy of Yu Hua’s Xiong di he’d left splayed open on the oak night table. “What is it?”

“We’ve received some tissue samples from Shanxi province.”

He held the phone in the crook of his neck as he unfolded his glasses and put them on. “And?”

“And you better come down here.”

Li felt his stomach knotting. He was the senior epidemiologist in the Ministry of Health’s Department of Disease Control. Cho, his assistant despite being twenty years older than Li, wouldn’t be calling him at this time of night unless—

“So you’ve done initial tests?” He could hear sirens off in the distance, but, still waking up, couldn’t say whether they were coming from outside his window or over the phone.

“Yes, and it looks bad. The doctor who shipped the samples sent along a description of the symptoms. It’s H5N1 or something similar — and it kills more quickly than any strain we’ve seen before.”

Li’s heart was pounding as he looked over at the clock, which was now glowing with the digits 4:44 — si, si, si: death, death, death. He averted his eyes and said, “I’ll be there as fast as I can.”

Dr. Kuroda had found Caitlin through an article in the journal Ophthalmology. She had an extremely rare condition, no doubt related to her blindness, called Tomasevic’s syndrome, which was marked by reversed pupil dilation: instead of contracting in bright light and expanding in dim light, her pupils did the opposite. Because of it, even though she had normal-looking brown eyes (or so she was told), she wore sunglasses to protect her retinas.

There are a hundred million rods in a human eye, and seven million cones, Kuroda’s email had said. The retina processes the signals from them, compressing the data by a ratio of more than 100:1 to travel along 1.2 million axons in the optic nerve. Kuroda felt that Caitlin having Tomasevic’s syndrome was a sign that the data was being misencoded by her retinas. Although her brain’s pretectal nucleus, which controlled pupil contraction, could glean some information from her retinal datastream (albeit getting it backward!), her primary visual cortex couldn’t make any sense of it.

Or, at least, that’s what he hoped was the case, since he’d developed a signal-processing device that he believed could correct the retinal coding errors. But if Caitlin’s optic nerves were damaged, or her visual cortex was stunted from lack of use, just doing that wouldn’t be enough.

And so Caitlin and her parents had learned the ins and outs of the Canadian health-care system. To assess the chances of success, Dr. Kuroda had wanted her to have MRI scans of specific parts of her brain (“the optic chiasma,”

“Brodmann area 17,” and a slew of other things she’d never known she had). But experimental procedures weren’t covered by the provincial health plan, and so no hospital would do the scans. Her mother had finally exploded, saying, “Look, we don’t care what it costs, we’ll pay for it” — but that wasn’t the issue. Caitlin either needed the scans, in which case they were free; or she didn’t, in which case the public facilities couldn’t be used.

But there were a few private clinics, and that’s where they’d ended up going, getting the MRI images uploaded via secure FTP to Dr. Kuroda’s computer in Tokyo. That her dad was freely spending whatever it took was a sign that he loved her … wasn’t it? God, she wished he would just say it!

Anyway, with time-zone differences, a response from Kuroda might come this evening or sometime overnight. Caitlin had adjusted her mail reader so that it would give a priority signal if a message came in from him; the only other person she currently had set up for that particular chirping was Trevor Nordmann, who had emailed her three times now. Despite his shortcomings, and that stupid thing he’d said, he did seem genuinely interested in Caitlin, and—

And, just then, her computer made the special sound, and for a moment she didn’t know which of them she most hoped the message was from. She pushed the keys that made JAWS read the message aloud.

It was from Dr. Kuroda, with a copy to her dad, and it started in his long-winded fashion, driving her nuts. Maybe it was part of Japanese culture, but this not getting to the point was killing her. She hit the page-up key, which told JAWS to speak faster.

“…my colleagues and I have examined your MRIs and everything is exactly as we had hoped: you have what appear to be fully normal optic nerves, and a surprisingly well-developed primary visual cortex for someone who has never seen. The signal-processing equipment we have developed should be able to intercept your retinal output, re-encode it into the proper format, and then pass it on to the optic nerve. The equipment consists of an external computer pack to do the signal processing and an implant that we will insert behind your left eyeball.”

Behind her eyeball! Eek!

“If the process is successful with one eye, we might eventually add a second implant just behind your right eyeball. However I initially want to limit us to a single eye. Trying to deal with the partial decussation of signals from the left and right optic nerves would severely complicate matters at this pilot-project stage, I’m afraid.

“I regret to inform that my research grant is almost completely exhausted at this point, and travel funds are limited. However, if you can come to Tokyo, the hospital at my university will perform the procedure for free. We have a skilled ophthalmic surgeon on faculty who can do the work…”

Come to Tokyo? She hadn’t even thought about that. She’d flown only a few times before, and by far the longest flight had been the one a couple months ago from Austin to Toronto, when she and her parents had moved here. That had taken five hours; a trip to Japan would surely take much longer.

And the cost! My God, it must cost thousands to fly to Asia and back, and her parents wouldn’t let her go all that way alone. Her mother or father — or both! — would have to accompany her. What was the old joke? A billion here, a billion there — before you know it, you’re talking real money.

She’d have to discuss it with her parents, but she’d already heard them fight about how much the move to Canada had cost, and—