Then, before I even had to explain, he stopped short and turned on his bedside light.

Of course… he whispered, Oh my God, of course.

Sure enough, in the photo I'd shown him, two little nubs stuck out the top of the statue's head, like goatish satyr horns.

Paul jumped down from the bunk, loudly enough that I waited for Gil and Charlie to appear. You did it, he said, eyes wide. This must be it.

He continued like that for a while, until I started to feel an uncomfortable sense of dislocation, wondering how Colonna could've put the answer to his riddle on a Michelangelo sculpture.

So why are they there? I asked finally.

But Paul was already far ahead. He yanked the book off his bunk and showed me the explanation in the text. The horns have nothing to do with being a cuckold. The riddle was literal: who gave Moses horns? It's from a mistranslation of the Bible. When Moses comes down from Mount Sinai, Exodus says, his face glows with rays of light. But the Hebrew word for 'rays' can also be translated as 'horns'-karan versus keren. When Saint Jerome translated the Old Testament into Latin, he thought no one but Christ should glow with rays of light-so he advanced the secondary translation. And that's how Michelangelo carved his Moses. With horns.

In all the excitement, I don't think I even sensed what was happening. The Hypnerotomachia had slunk back into my life, ferrying me across a river I never intended to cross. All that stood in our way was figuring out the significance of Saint Jerome, who had applied the Latin word cornuta to Moses, thus giving him horns. But for the following week, that was a burden Paul happily took upon himself. Beginning that night, and continuing for some time, I was only a hired gun, his last resort against the Hypnerotomachia. I thought it was a position I could keep, a distance I could maintain from the book, letting Paul play the middleman. And so, as he returned to Firestone, white-hot with the possibilities of what we'd found, I went off and made another discovery of my own. Still strutting after my encounter with Francesco Colonna, I can only imagine the impression I made on her.

We met where neither of us belonged, but where both of us felt at home: Ivy. For my part, I'd spent as many weekends there as I had at my own club. For hers, she was already one of Gil's favorites, months before bicker for her sophomore class began, and it was his first thought to introduce us.

Katie, he said, after getting both of us to the club on the same Saturday night, this is my roommate, Tom.

I gave a lazy smile, thinking I didn't have to flex much muscle to charm a sophomore.

Then she spoke. And like a fly in a pitcher plant, expecting nectar and finding death, I realized who was hunting who.

So you're Tom, she said, as if I met the description of a convict from a post office wall. Charlie told me about you.

The best part about being described to someone by Charlie is that things can only get better from there. Apparently he'd met Katie at Ivy several nights earlier, and when he realized that Gil intended to make the match, he eagerly chipped in with details.

What did he tell you? I asked, trying not to look concerned.

She thought for a second, searching for his exact words.

Something about astronomy. About stars.

White dwarf, I told her. It's a science joke.

Katie frowned.

I don't get it either, I admitted, trying to undo my first impression. I'm not much for that kind of stuff.

English major? she asked, as if she could tell.

I nodded. Gil had told me she was into philosophy.

She eyed me suspiciously. Who's your favorite author?

Impossible question. Who's your favorite philosopher?

Camus, she said, even though I meant it rhetorically. And my favorite author is H. A. Rey.

The words came out like a test. I'd never heard of Rey; he sounded like a modernist, a more obscure T.S.Eliot, an uppercase e. e. cummings.

He wrote poetry? I ventured, because I could imagine her reading Frenchmen by firelight.

Katie blinked. Then for the first time since we'd met, she smiled.

He wrote Curious George,'1'' she said, and laughed out loud when I tried not to blush.

That was the recipe of our relationship, I think. We gave each other what we never expected to find. In my earliest days at Princeton I had learned never to talk shop with my girlfriends; even poetry will kill romance, Gil had taught me, if you mistake it for conversation. But Katie had learned the same lesson, and neither of us liked it. Freshman year she dated a lacrosse player I'd met in one of my literature seminars. He was smart, taking to Pynchon and DeLillo in a way I never did, but he refused to speak a word about them outside of class. It drove her crazy, the lines he drew through his life, the walls he put up between work and play. In twenty minutes of conversation that night at Ivy, we both saw something we liked, a willingness to have no walls, or maybe just an unwillingness to keep them standing. It pleased Gil that he'd made such a good match. Before long I found myself waiting for the weekends, hoping to run into her between classes, thinking of her before bed, in the shower, in the middle of tests. Within a month, we were dating.

As the senior in our relationship, I imagined for a while that it was my job to apply the wisdom of my experience to everything we did. I made sure we kept to familiar places and friendly crowds, having learned from past girlfriends that familiarity always arrives in the wake of infatuation: two people who think they're in love can find out, when left alone, exactly how little they know about each other. So I insisted on public places-weekends at eating clubs, weeknights at the student center-and agreed to meet at bedrooms and library nooks only when I thought I detected something more in Katie's voice, the come-hither registers I flattered myself I could hear.

As usual, it was Katie who had to straighten me out.

Come on, she told me one night. We're going to dinner together.

Whose club? I asked.

A restaurant. Your choice.

We'd been together for less than two weeks; there were still too many parts of her I didn't know. A long dinner alone sounded risky.

Did you want to ask Karen or Trish to come along? I asked. Her two roommates in Holder had been fail-safe company. Trish, in particular, who never seemed to eat, dependably talked through any meal.

Katie's back was turned to me. We could ask Gil to come too, she said.

Sure. It struck me as an odd combination, but there was safety in numbers.

What about Charlie? she asked. He's always hungry.

Finally I realized she was being sarcastic.

What's the problem, Tom? she said, turning back to me. You're afraid other people will see us alone?

No.

I bore you?

Of course not.

Then what? You think we'll find out we don't know each other very well?

I hesitated. Yes.

Katie seemed amazed that I meant it.

What's my sister's name? she said finally.

I don't know.

Am I religious?

I'm not sure.

Do I steal money from the tip jar at the coffee shop when I'm short on change?

Probably.

Katie leaned in, smiling. There. You survived.

I'd never been with someone who was so confident about getting to know me. She never seemed to doubt the pieces would fit. Now let's go to dinner, she said, pulling me by the hand. We never looked back.

Eight days after my dream about the satyr, Paul came to me with news. I was right, he said proudly. Parts of the book are written in cipher.

How'd you figure it out?

Cornuta— the word Terome used to give Moses horns-is the answer Francesco wanted. But most of the normal techniques for using a word as a cipher don't work in the Hypnerotomachia. Look…