Lucinda Mandelbaum had, on the spot, not only devised an alternative explanation that undermined the claims of the presenter, but, in the best scientific tradition, had also conceived a way of testing the two alternative hypotheses. And it had all come out so smooth and polished- frankly, a lot more coherent than the delivered lecture itself. Cass thought there might have been a scattering of applause following her rejoinder, although he couldn't be sure that he hadn't projected his own silent ovation onto the external world.

Cass, ravished, followed the ensuing dialogue between the astonishing Lucinda and the atomizing Lipkin. There was no doubt in Cass's mind, as he was sure that there was no doubt in anyone's mind, including Lipkin's, that Lucinda got the better of the man, whom Cass now actively disliked for keeping up his increasingly whining refusal to accept Lucinda's brilliant counter-explanation.

Pavel Yarnau, the smarmy chair of the Psychology Department, finally called a halt to the heated Q & A, thanking "our speaker for providing us all with such a lively time and much food for thought. And now let's continue the discussion over more mundane fare, not to speak of drink. I ask you all to join me upstairs in the Leah and Marty Feingold Room for the reception in honor of Professor Lipkin."

"Well, this has been fun," Lucinda said to Cass as they were both standing, waiting for their row to clear out so that they could proceed. Did she mean merely Lipkin's talk or the communion between them? Her eyes were scanning the crowd. "Are you going to that dinner for Lipkin?" she asked without really looking at him.

"No, I didn't sign up."

Cass rarely put his name on the sign-up sheets that had slots for ten faculty members and four graduate students to entertain the speaker at one of the local restaurants that had sprouted up along the formerly decrepit and now almost hip Maudlin Street. With the inflated property values of Cambridge and Boston driving chefs to outlying areas, Weedham, Massachusetts, was enjoying a restaurant renaissance, trendy little spots blossoming amid the blight.

"Well, then, I guess I'll see you soon," and she turned away, apologetically squeezing past the colleagues over whom she'd just recently stepped. Cass stood there watching her as she strode up to the podium. She and Lipkin shook hands cordially, even enthusiastically. Lucinda was smiling broadly as she spoke to him, and he was laughing as he answered her. There were obviously no hard feelings between these MVPs.

Cass watched for a while, his head cocked and his crooked smile in place, until everybody started heading out to the reception, lining up behind Lipkin and Lucinda like retinue behind royalty. Cass skipped the reception, and went home happy, chewing over it all. It wasn't so much food for thought. It was ambrosia.

He saw Lucinda Mandelbaum two days later, at a university building where faculty meetings were held. She was standing next to Sebastian Held, both of them tanking up on caffeine in the few minutes before the meeting began.

Cass hated faculty meetings and skipped as many as he could get away with. Watching his colleagues' intense engagement in the proceedings, the eloquence and pedantry slathered on points too minute for any but the best-trained minds to discern, he would be overtaken by his own failure to grasp human nature. But today he had looked forward to coming.

Lucinda, dressed in a pair of tailored black slacks and a pale-gray sweater matching the color of her eyes, seemed deep in conversation with Sebastian Held, but Cass strode right over and greeted them both enthusiastically.

"Hello," Lucinda had said, smiling back at him with formally polite blankness, reaching out her hand to shake his with a briskly firm shake. "Lucinda Mandelbaum."

"Yes, of course. I'm Cass. Cass Seltzer."

"Nice to meet you, Cass."

"Oh, we've already met," he said, stopping himself before he could wail out his dismay: Don't you remember? Don't you remember how we laughed together like careless gods?

"Oh, sorry. I'm terrible with faces. Remind me of what you do?"

"Psychology of religion."

"Psychology of religion?" Her thin upper lip curled slightly, not quite achieving a smile. "As a branch of abnormal psychology? Or are you one of those people who try to offer an evolutionary explanation for group madness?"

"Well, not exactly. What interests me more is the phenomenology of religion in all its varieties. What does it feel like from the inside? What sorts of terrors does it address, and what sorts of emotional growth does it both block and enhance? And how does the religious response manifest itself, even in ways that may not seem religious?"

Her lip curled a bit more, and it was a smile, and she lifted her chin so that her throat was exposed.

"It must be frustrating to deal with irrationality."

"How can one be a psychologist and not deal with irrationality?"

"If I thought that were true, I'd never have gone near the field."

"Well, I guess it's a good thing for the field, then, that you don't think it's true."

"But is it a good thing for the field that you do?"

Cass studied her face, which seemed both serious and friendly. He couldn't tell from it, or from her serious and friendly voice, whether her question was ingenuous or sarcastic. Either way, he didn't know how to respond. Lucinda held his gaze for several more ambiguous moments and then turned back to Held to resume their interrupted conversation.

He didn't say more than ten words to Lucinda, nor she to him, for the rest of the semester.

Autumn and winter had gone by without his taking much notice. He must have shown up and taught his classes; he had his students' class evaluations to prove it. And they were pretty good evaluations, too, considering he couldn't remember a thing about the classes, neither preparing for them, nor giving them, nor reading the papers and grading the exams he had apparently assigned and administered. He had done it all sleepwalking with his eyes open, instructing the youth by day and writing, writing, writing by night.

Lucinda's question to him, so direct and so undecipherable, had stunned him, and he needed to answer her. He needed to extract some answer out of the questions that had been roiling in him for the past two decades, the questions that he had lived out with Jonas Elijah Klapper and the questions he had lived out with Azarya. He had never cashed in that experience for hard insight.

Had he tried out any of his new thoughts on his students? He couldn't remember, but a few of the more perceptive class evaluations had spoken of how it was cool to watch Professor Seltzer arguing with himself. "Sometimes it could get a little weird, like that dude at the end of Psycho. But in a good way."

No doubt he had been distracted. It had been all he could do just to keep up with his classes and his fantasies. He never skimped on his fantasies, no matter how busy he was. He didn't need to, since they blended with all he saw and thought and wrote and said. It was the love of the impossible that made everything possible. He was battered by the beating wings of unlimited desire, but they lifted him, too. Battered, emboldened, and exalted, and all at once.

Mona was convinced, despite his disclaimers, that he had stopped attending the Psychology Outside Speaker lectures because he couldn't stand the circus they had become-"what with that Mandelbaum creature performing in all three rings at once, juggler, lion-tamer, tightrope walker, bareback horseback rider, lady on the flying trapeze ..."

"That's five rings, Mona."

"And counting. She's such an insufferable showoff. She's destroyed the whole atmosphere of our department. Do you know, that pig Pavel doesn't even go through the motions of asking for questions anymore? He just turns to her with an obscene leer and squeals, 'Lucinda?' and the whole place cracks up, including the star-by which I don't mean the outside speaker. It's revolting. The whole display is revolting. Everybody bows down to that creature, and only because she's a bully."

"Surely there's more to it than that."

"You mean the fucking Mandelbaum Equilibrium? Cass, you think anybody here understands it better than you and me? They don't know the Mandelbaum Equilibrium from e = fucking mc2. For all they know, it's got as much to do with psychology as my grandmother's blintzes. It's not like mindfulness. Just because everybody can understand mindfulness, and can't understand what the Mandelbaum Equilibrium is even about, they let her get away with carrying on as if the rest of us are just her movable props. Do you know, people have told me that they have to keep introducing themselves to her over and over again, because she's just not mindful enough to remember who anyone here is? For some reason, she always seems to remember me, though. I'm one of the few whose names she actually knows, although for some reason she seems to think I'm Hungarian."

Cass had been surprised by Mona's severity toward Lucinda, especially since he had heard Mona complaining that people don't let women academics get away with the kind of high-handedness that their male counterparts habitually employ. He would have thought Mona would be the first to applaud Lucinda for her ballsiness.

Cass had barely been on campus fall semester. He'd taken a leave of absence because of the extensive book tour the publisher had set up for him: twenty-one cities in two months, and then another month spent in England, Scotland, and Ireland. He'd kept in touch through sporadic e-mail with Mona, who tried mindfully to keep the communications focused on him, "who, after all, is the only one of the two of us who's suddenly leading the life of Cindefuckingrella."

He had returned from London only a few days before. He was coming to campus now to gather any mail that might have accumulated. It was the Wednesday before Thanksgiving, and it was already evening, and the campus was deserted except for a few foreign students forlornly clumping here and there, their footsteps echoing with melancholia on the abandoned Frankfurter concrete. The moodiness of an early evening in late November softened the hard outlines of the aggressive architecture. The bluing air was crisped and smoke-sweetened, and the leaves crunched gratifyingly under his feet as he walked up the dirt path from the faculty parking lot that was closest to the Katzenbaum Brain and Cognitive Sciences Center.

The Katzenbaum Center was built in the style that prevailed on Frankfurter's campus, meaning that it was a rectilinear, flat-roofed building, made of red brick with an exposed steel structure, a large show of glass, and a generous helping of concrete, which was stained red to match the bricks. The campus went heavy on the concrete. This, Cass had been told, was the International Style of architecture, which had been considered boldly cutting-edge after the Second World War, when Frankfurter had been established, its Master Building Plan embarked upon. To Cass it looked like the style of architecture favored by the wealthy Reform temples and Jewish community centers of northern New Jersey, where he had grown up. He associated this architecture less with Le Corbusier than with Hadassah. The founders of the school, together with the money they had raised, had been Jewish, and the school, though non-denominational, still attracted a disproportionate number of Jewish students.

Cass was just opening the heavy glass door when Lucinda materialized on the other side of it. She had taken the stairs down from her sixth-floor office rather than using the elevator. He saw the dark figure swiftly descending, almost a blur of motion, though he hadn't realized that it was she. Why would he have realized, when a hundred times a day he had seen her superimposed on his surroundings?

The vision of Lucinda was always whisper-close, her phantom elbow ready to poke him playfully in the ribs. She had stood beside him on a sidewalk in Portland, Oregon, staring up at his illuminated name on the marquis of a big old opera house that he would be speaking in that night, both of them shaking their heads at the incongruity. She had walked the moonlit fog in London, floated by his side in fabled Oxford, teased him about his debate with Sir Jonathan Sacks, the Chief Rabbi of Great Britain, at London's Jewish Book Festival, on reason and faith. So why wouldn't he see her now, approaching him across the sterile vestibule of Katzenbaum, as he stood there holding the door wide open for whoever it really was?

She must have felt the cool, crisp air sweeping in. She looked up at the man standing there holding the door for her, his head tilted to one side and a loopy smile wobbling about on his pleasantly discomfited face.

He expected that she wouldn't recognize him. He would simply smile at her without saying a word, as he held the door so that she could pass him by and disappear into the darkening world.

Lucinda looked up into his face, did a double take, and then burst out laughing.

"What?" he said. He could feel his embarrassingly responsive complexion beginning a slow burn. He had said nothing, and already she was laughing at him.

Without a word, she reached into her satchel and pulled out the familiar book, with its laminated foil jacket. It was a jolt of intimacy to see his progeny emerging from out of her bag.

"I'm not very good with faces, but I'd be willing to bet good money that you're the author of this book. Wait a minute." She opened the back flap and held the picture side by side against the original, the soft cuff of her winter coat slightly caressing his blazing cheek. "Yes. Don't deny it. You penned this tome. You're Cass Seltzer!"

"You're reading it."

"Not really. I've simply incorporated it into my weight-lifting regimen."

"That's why I added all those extra arguments for God's existence. The publisher was supposed to mention its physical-training possibilities on the back cover."

"I find it makes a rather good stepladder, too. Easily transported from room to room. Had you intended that as well?"

"As a stepladder to enlightenment!"

Lucinda laughed, throwing back her head. She had a brave and sweeping peregrine of a laugh. And just like that it was back, reconstituted, the sense of blessed ease they had shared inside that dappled afternoon. Cass felt the way her whispering breath had warmed his ear.

"Aren't you going to ask me whether I like your book? Or are all other opinions beside the point now that the New York Times has found it 'invariably engaging and provocative,' and The New York Review of Books has described you as 'the William James for the twenty-first century'?"

He couldn't believe it. She had actually memorized the choice bits from his reviews that were used in the ads for the book. Not even his mother had memorized the quotes.

"I'm afraid to ask you what you think of it. I'm afraid you're going to fang me."

"You don't have to worry about that. The fanger of my fangee is my friend."

"Funny, I don't think of myself as a fanger."

"Oh, but you are, my friend, a fanger of no mean talent. You fanged God!"

"Can I have them quote that on the cover of the paperback? 'A fanger of no mean talent: Lucinda Mandelbaum, author of the Mandelbaum Equilibrium.'"

She quickly cast her eyes downward, so that her long lashes rested on the ridge of her cheekbones for a few seconds, and when she raised her eyes again it was with a different expression altogether.

Lucinda's lips were thin, and if there was any imperfection in her face, it was in her stiff upper lip. But now her upper lip quivered slightly, and the transformation was complete. It was a thing counter, original, spare, and strange, what had happened to her face. He could imagine no face more beautiful in all the world, no face more touching in its exposure. He could never go back and recover the face that had been there only moments before.

"Thank you," she whispered.

"For what?" he whispered back.

"For saying that that's who I am. That that's who I still am, even if I'm here."

Cass could have taken offense, but he didn't. With that strong sense of gazing directly into another, soul to soul, of seeing it all and all at once, as if it were an endless vista laid out before his eyes, he grasped the sorrows behind Lucinda.

Her move to Frankfurter had obviously cost her dearly, but she never let on. She could have just bided her time here instead of giving it- giving them-everything she had. There was nobody at Frankfurter she needed to impress. But she carried on as she always had, performing at peak, a prizefighting champ. And just for the sheer sport of the thing, for the reasons sustained in her own ardent heart. She wasn't competing against anyone but herself. That's what people like Mona didn't get. He hadn't altogether gotten it himself until this moment of seeing straight through to the soul of her.

Lucinda Mandelbaum, of the famous Mandelbaum Equilibrium, just kept playing the game with her heart and soul, making everybody here feel that by her very presence they had all been admitted into the insider game, when all the while she was aware that that insider game was transpiring elsewhere, away from Frankfurter and away from Lucinda Mandelbaum, and maybe she would never get herself back into it the way she had been, the way she had been born to be.

That transformed face of hers that she was holding out to him told him everything. It was astounding that she would trust him with the sight of it. What had he done to earn the trust of Lucinda Mandelbaum?

He saw the fragility within the fanger, the willed boldness and gumption of this brave and wonderful girl.

He saw the dappledness of her.

Glory be to God for dappled things, he silently quoted his second-favorite poet.

IV.

The Argument from the Irrepressible Past.

Despite the metaphysical exertions of his night, suspended over sublimity on Weeks Bridge, Cass remembers that he has a meeting with Shimmy Baumzer at eleven in the morning. So, before settling down again beneath the luxury of Lucinda's comforter, he sets his alarm for 9 a.m., and then, just to be safe, he sets the second alarm clock, on Lucinda's side. It's already after six, the bedroom on the top floor of the duplex brightening, and he wonders whether he'll be able to fall asleep at all, hugging the last tattered bits of epiphany and Lucinda's fragrant pillow ... and is awakened into terrifying confusion, the awful ringing setting his frantic heart to pounding, while he is desperately trying to make it stop, scuttling back and forth across the mattress, fumbling with the two alarm clocks-which one the hell is it?-until he finally realizes it isn't an alarm clock at all.

It's the telephone.

"Hello?"

"It's me!"

"Lucinda?"

"Lucinda? Who the hell is Lucinda? It's me! Roz!"

"Roz Margolis?"

"Is there another?"

"Roz. My God. Roz. My God."

"For a famous atheist, you sure call out to the deity often enough there, sweetie."

Roz is laughing, girlish peals that contrast with her husky voice. It brings her home to him as nothing else could. Say what you will about Roz Margolis, she certainly knows how to laugh.

"Roz," he repeats. There's still some small chance he's dreaming.

Roslyn Margolis had been Cass's girlfriend years ago, when he had first come to Frankfurter to study with Jonas Elijah Klapper. She had spent ten months at Harvard, and that's how long she and Cass had been together. Still, those ten months had been something. They had been so packed with drama that they had left the impression of being ten years, ten decades, ten eternities.

They had never lost touch. Over the years, he had been wakened often enough in the middle of the night to answer the phone and hear Roz on the other end, always calling from some remote time zone, miscalculating the hour that it was for Cass, apologizing profusely in between her laughter and questions and unbelievable news. News from Roz always came filed under "Unbelievable."

"Cass, I can't believe how famous you've suddenly gotten yourself. It's incredible! I've heard you on NPR at least a hundred times. And I read that feature in Time magazine. The atheist with a soul! Since when are you an atheist? I remember when you were contemplating the Kabbalistic meaning of potato kugel!"

"Where are you calling from, Roz? Are you still studying the fearsome people of the Amazon rain forest?"

"No. I'm here!"

"Where 'here'?"

"Cambridge! I'm studying the fearsome people of Cambridge!"

"What are you doing here?"

"It's a good thing I'm not the sensitive type, Cass. You're supposed to be shouting out, 'Yippee! Glory be! Hallelujah!' Or whatever you atheists with souls call out in your ecstasy!"

Cass moves the phone receiver slightly away from his rattled ear. He's becoming increasingly convinced that this is no dream.