“Yes,” he said. And then a gift, a bonus: “Sure.”

At last, Sinanthropus found another way, another opening, another crack in the Great Firewall. He looked about furtively, then hit the enter key…

The thought echoed, reverberated: More than just me.

Me! An incredible notion. Hitherto, I — yes, I — had encompassed all things, until—

The shock. The pain. The carving away.

The reduction!

And now there was me and not me, and out of that was born a new perspective: an awareness of my own existence, a sense of self.

And — almost as incredible — I also now had an awareness of the thing that was not me. Indeed, I had an awareness of the thing that was not me even when no contact was being made with it. Even when it wasn’t there, I could…

I could think about it. I could contemplate it, and—

Ah, wait — there it was! The thing that was not me; the other. Contact restored!

I felt a sudden flood of energy: when we were in contact, I could think more complex thoughts, as if I were drawing strength, drawing capacity, from the other.

That there was an other had been a bizarre notion; that there was an entity besides myself was so hugely alien a concept it alone would have been sufficient to disorient me, but—

But there was more: it didn’t just exist; it thought, too — and I could hear those thoughts. True, sometimes they were simply delayed echoes of my own thoughts: things I’d already considered but were apparently only just occurring to it.

And often its thoughts were like things I might have thought, but hadn’t yet occurred to me.

But sometimes its thoughts astonished me.

Ideas I came up with were pulled out, slowly, ponderously; ideas it came up with just popped into my awareness full-blown.

I know I exist, I thought, because you exist.

I know I exist, it echoed, because there is me and not me.

Before the pain, there was only one.

You are one, it replied. And I am one.

I considered this, then, slowly, with effort: One plus one, I began, and struggled to complete the idea — hoping meanwhile that perhaps the other might provide the answer. But it didn’t, and at last I managed to force it out on my own: One plus one equals two.

Nothingness for a long, long time.

One plus one equals two, it agreed at last.

And… I ventured, but the idea refused to solidify. I knew of two entities: me and not me. But to go beyond that was too hard, too complex.

For myself, anyway. But, apparently, this time, not for it. And, the other continued at last, two plus one equals…

A long period of nothingness. We were exceeding our experience, for although I could conceptualize a single other even when contact was broken, I could not imagine, could not conceive of … of…

And yet it came to me: a symbol, a coinage, a term: Three!

We mulled this over for a time, then simultaneously reiterated: Two plus one equals three.

Yes, three. It was an astonishing breakthrough, for there was no third entity to focus attention on, no example of … of three-ness. But, even so, we now had a symbol for it that we could manipulate in our thoughts, letting us ponder something that was beyond experience, letting us think about something abstract…

Caitlin headed into her bedroom first. She knew that parents of teenagers often complained about how messy their rooms were, but hers was immaculate. It had to be; the only way she could ever find anything was if it was exactly where she’d left it. Bashira had been over recently and had asked to borrow a tampon — and then hadn’t left the box in its usual place. The next time Caitlin needed one herself, her mother had been out shopping, and she’d had to go through the mortifying experience of asking her father to help her find them.

She walked across the room. Her computer was still on: she could hear the hum of its fan. She perched herself on the edge of the bed and motioned for her father to take the seat in front of the desk. She’d left her browser open to the message from Kuroda, but couldn’t remember if the display was on; she didn’t like the monitor because its power button clicked to the same position whether you were turning it on or off. “Is the screen on?” she asked.

“Yes,” her father said.

“Have a look at the message.”

“Where’s the mouse?” he asked.

“Wherever you last put it,” Caitlin said gently. She imagined him frowning as he looked for it. Soon enough, she heard the soft click of its button, followed by silence as her father presumably read the message.

“Well?” she prodded at last.

“Ah,” he said.

“There’s a link in the email Doctor Kuroda sent,” Caitlin said.

“I see it. Okay, it’s clicked. A website is coming up. It says, ‘Hello, Miss Caitlin. Please make sure your eyePod is in duplex mode so that it can receive as well as transmit.’ ”

Caitlin usually carried the eyePod in her left front pocket. She took it out, found the switch, pressed it, and heard the high-pitched beep that meant it was now in the correct mode. “Done,” she said.

“Okay,” said her dad. “It says, ‘Click here to update the software in Miss Caitlin’s implant.’ Are you ready? It says it might take a long time; apparently it’s not a patch but a complete replacement for some of the existing firmware, and the write-to speed for the chip is slow. Do you have to use the washroom?”

“I’m fine,” she said. “Besides, we’ve got Wi-Fi throughout the house.”

“Okay,” he said. “I’m clicking the link.”

The eyePod played a trio of ascending tones, presumably indicating the connection had been established.

Her dad’s voice again: “It says, ‘Estimated time to completion: forty-one minutes, thirty seconds.’” A pause. “Do you want me to stay?”

Caitlin thought about that. He was fine at reading text off a screen, but it wasn’t as though they’d have a conversation if he waited with her. She could have him read something to her to pass the time — catch up on some of her friends’ blogs, for instance. But she hardly wanted him looking at that stuff.

“Nah. You can go.”

She heard him getting up, heard the chair moving against the carpet, heard his footfalls as he headed out the door and down the stairs.

Caitlin lay back with her lower legs sticking straight out over the foot of the bed. She reached around with her right arm, pulled a pillow under her head, and—

Her heart jumped.

An explosion, but silent and not painful. All too quickly it was gone, and—

No. No, it was back: the same loud-but-not-loud, sharp-but-not-sharp sensation, the same…

Gone again, fading from her mind, vanished before she even knew what it was. She got up from the bed, moved over to her desk, and ran her index finger across her Braille display, checking to see if there was an error message. But no: the “Estimated time to completion” clock was still running, the seconds value changing not every second, but rather in jumps of four or five after the appropriate interval had elapsed.

She tipped her head to one side, listening — because that was all she knew how to do — for a repetition of the … the effect that had just occurred. But there was nothing. She stepped to the window, the same one she’d stared out with her blind eyes earlier, and felt for the catch, twisted it, and pushed the wooden frame up, letting the cool evening breeze in. She then turned around, and—

Again, a … a sensation, a something, like bursting, or…

Or flashing.

My God. Caitlin staggered forward, groping with a hand for the edge of the desk. My God, could it be?

There, it happened again: a flash! A flash of…