I'd paid particularly close attention to Mary's report that Robert Oliver had first met the woman of his obsession in a crowd at the Metropolitan Museum of Art, and now I considered whether I could ask Robert about the incident directly. Whatever had happened there, whatever he had seen in her, had absorbed much of his attention--and probably shaped his illness--since then. If he had imagined the woman in that crowd at the Met--in other words, if she had been his hallucination, this would imply a rethinking of my diagnosis of Robert, and a serious shift in his treatment. Did he now paint from memory, whether he'd originally seen a real woman or not? Or was he still hallucinating? The fact that he was apparently painting a modern woman, glimpsed once, in nineteenth-century clothing, implied in itself some act of imagination, perhaps involuntary. Did he have other hallucinations? If he did, he wasn't painting them, at least not at the moment.

Whatever the case, by the time of his move to Greenhill with Kate, he'd been imagining the woman's face at least occasionally; after all, Kate had found a sketch of her in Robert's shirt pocket during their drive south. But if I asked Robert about his first sighting of the woman and included any information about the museum, he would know at once that I'd been talking with someone he was close to, and the pool of possibilities would be very small, then--perhaps a pool of one, since he already knew I had Mary's last name. He appeared to have confided in Mary but not Kate and was unlikely to have talked with anyone else at all, unless he'd had friends in New York to whom he might have mentioned his unforgettable first sight of the woman. He'd implied to Mary that he'd seen the stranger only a few times, but I found that difficult to believe, especially after viewing those powerful paintings at Kate's. Surely he'd known her intimately and absorbed her face and presence over time. Robert claimed he didn't work from photographs, but might he have been able to persuade a stranger to model live for him until he had enough material to work from for future portraits?

But I couldn't risk asking Robert any of this; if I revealed the extent of my knowledge to him, I'd never win his trust. My telling him I knew Mary's name had probably been an error. I did go so far as to inquire, during one of my morning visits to the big armchair in his room, where he'd first gotten to know the woman who inspired most of his work. He looked briefly at me, then went back to the novel he was reading. After a while I could only excuse myself and wish him a good day. He'd taken to borrowing crime thrillers from the shelves of well-thumbed paperbacks in the patients' sitting room, reading them with a kind of bored dedication when he wasn't painting; he chewed up about one a week, and they were always the crudest kind of potboiler about the Mafia, or the CIA, or murder mysteries set in Las Vegas.

I had to wonder whether Robert felt some kind of sympathy for the criminals in these books, since he'd been arrested himself with a knife in his hand. Kate had said he sometimes read thrillers, and I'd seen them on his office shelves, but she'd also said he read exhibition catalogs and works of history. There were much better books than those detective novels in the patients' sitting room, including some biographies of artists and writers (I confess I tucked a few of those into the shelves myself, to see if he'd pick them up), but he never touched them. I could only hope that he wasn't acquiring any further taste for violence, from tales of murder, although I saw no signs of it. He was as unlikely to tell me where and how he'd encountered his favorite model as to explain why he limited his reading to the very dregs of the sitting-room shelf.

Mary's story about his first glimpse of his lady had given me another thought, however, and perhaps it was also her reminding me laughingly of the genius of Sherlock Holmes that made me hold that little tale up to the light again and again. I even called Mary one day and asked her to repeat the story as Robert had told it to her at Barnett College, and she did, in very nearly the same words. Why was I asking? She had promised to explain more later, and she would. I thanked her politely, acknowledging the installments she was sending and careful not to press her for a meeting of any sort.

I couldn't shake my feeling about that moment, however, and a Holmesian idea about it took hold of me--a particular suspicion, but also a sense that, on principle, one should go see the scene of the event for oneself. It was just the Met, and I'd been there many times over the years, but I wanted to find the spot of Robert's first hallucination, or inspiration, or--had it been falling in love? Even if there was no gun at the scene, no bit of rope hanging from the ceiling, nothing one could pull out a magnifying glass to examine--well, it was silly, but I would go, partly because I could combine it with a more important mission, a visit to my father. I hadn't been up to Connecticut in nearly a year, which was six months too long, and although he sounded cheerful on the phone and in the little notes he sent on his parish stationery (it needed using up, he said, and he disdained e-mail), I worried that if anything was wrong he'd never tell me by any of those media. And what might be wrong, if something really was, would likely be a drooping of his spirits, which he certainly wouldn't report.

With all this in mind, I chose an upcoming weekend and bought two train tickets, one a round-trip to Penn Station from Washington, and the other a loop up to my hometown and back to New York. I splurged on a reservation for a night in a dingy but pleasant old hotel near Washington Square, a place I'd once spent a weekend with a young woman I'd half expected to marry; surprising, now, how long ago that had been and how much I'd forgotten about her, a woman I'd once embraced in a hotel bed and with whom I'd sat on the benches in Washington Square Park while she pointed out all the species of trees that grew there. I didn't know where she was now; probably she'd married someone else and become a grandmother.

I thought fleetingly of inviting Mary to go with me to New York but couldn't puzzle out what that might entail or how she'd take it, how I could solve or even bring up the matter of hotel rooms. It might have been appropriate to go to the museum with her, since Robert Oliver's past consumed her even more deeply than it did me. But it was too much of a conundrum. In the end I didn't tell her about my plans; she hadn't called in a couple of weeks anyway, and I assumed she'd get more of her account of Robert to me when she was ready. I'd call her on my return, I decided. I told my staff that I would miss one day of work to see my father, and then I gave the usual orders for Robert and my other worrisome patients to be watched with special care.

I went straight from Penn Station to Grand Central to catch the Metro-North New Haven Line; I'd have a long overnight with my father before my visit to the city. It's not a bad ride, and I've always liked the train, which I use for both reading and daydreaming. This time I read some of the book I'd brought, a translation of The Red and the Black, but also watched the early-summer scenery go by, the miserably damaged heart of the Northeast Corridor, brick warehouses, the backyards of railroad neighborhoods in small towns and city suburbs, a woman hanging up laundry in slow motion, kids on an asphalt school playground, a towering landfill with gulls circling above it like vultures, the glitter of metal sticking out of the ground here and there.

I must have drowsed, because the sun was lighting up salt water by the time we reached the Connecticut coast. I've always loved that first glimpse of Long Island Sound, the Thimble Islands, the old pilings, the marinas full of shiny new boats. I grew up on this coast, more or less; our town is ten miles inland, but a Saturday in my childhood meant a picnic at the public beach in nearby Grant-ford, or a stroll on the grounds of Lyme Manor, or a walk along marsh roads that ended in some little platform from which you could view red-winged blackbirds through Mother's binoculars. I've never lived far from the smell of salt water, or its tributaries.

Our town, in fact, was built on a bank of the Connecticut River that the British would have taken by fire in 1812 had not the town's leading citizens hurried down to negotiate with the British captain, at which point the captain discovered that the mayor was his father's cousin and there was some quiet bowing and exchanging of home news. The mayor asserted his general willingness to acknowledge the king, the captain overlooked the obvious halfheartedness of his cousin's declaration, and everyone parted friends. That evening the town gathered in the church--not my father's but a very old one that stands right on the water--to offer thanks. The towns all around them fell to the British torch, and the mayor took in and sheltered their citizens with what must have been generosity but also guilt. Our town is the pride of the local historic preservationists: our churches and inn and oldest houses are original--virgin timber, spared by the ties of family. My father loves to tell that story; I wearied of it as a child but never fail to remember and feel moved by it when I see the water of the river again and the cluster of colonial structures, many of them now shops full of expensive candles and handbags, in the old center.

The railroad came in only thirty years after the gentlemanly captain left, but it arrived at the other end of town. The earliest station is long gone, and there's a fine building from about 1895 in its place; the waiting room -- brass, marble, dark wood--has exactly the smell of furniture wax it had when my parents and I waited for the train that would take us to New York to see the Christmas show at Radio City Music Hall in 1957. Today, a couple of passengers were reading the Boston Globe on the wooden benches I had loved before my feet could even reach the floor.

My father was waiting there for me, his tweed hat in one papery, transparent hand, his blue eyes bright and pleased when they found my face. He gave me a hug, a squeeze on the shoulders, and held me back for viewing, as if I might still be growing and he needed to check my progress. I smiled, wondering if he saw me with all my hair still brown and on my head, or with the flannel pants and bulky sweater I wore home from college, instead of seeing a man in his fifties, reasonably trim, in plain slacks and a polo shirt, a weekend jacket. And I felt that familiar pleasure of being someone's grown child. It shocked me that I hadn't seen him in so long; in previous years I'd come up more often than this, and I resolved on the spot to visit again much sooner. This man of nearly ninety was my proof of the continuity of life, the buffer between me and mortality--immortality, he would have said with a chiding smile, the clergyman in him tolerating the scientist in me. I had little doubt he'd go to heaven when he left me, although I hadn't believed in heaven since I was ten. Where else could such a person end up?

It occurred to me as I felt his arms around me that I already knew all the trauma that accompanies a parent's death, and knew also that the trauma of losing my father when the time came would be deepened by the earlier loss of my mother, of our shared memories of her, and by the fact that he was my last caretaker, the second to go. I'd helped patients through such passages, in fact, and their grief was often lingering and complex; after I'd lost my mother I'd come to understand that even the quietest slipping away of parental presence could be a devastation. If there were more serious symptoms in a patient, some ongoing struggle with mental illness, a parent's death could tip delicate balances, break down carefully maintained coping patterns.

But none of my professional understanding could console me ahead of time for the eventual loss of this mild, white-haired man in his lightweight summer coat, with his mingled optimism and cynicism about human nature, his calm ability to pass his vision test year after year despite the doubtful glances of the DMV clerks. When I saw him standing in front of me now, eighty-nine this fall and yet so much himself, I was seeing both his presence and his looming absence. When I saw him waiting for me in his good clothes, the bulge of car keys and wallet in his pants pockets, his shoes polished, I felt as always both his reality and the thin air that would one day replace him. In a strange way, I sometimes believed that he would not be complete for me until he was gone, perhaps because of the suspense of loving someone at the far edge of life.

While he was still here, I hugged him back solidly--hard, even--surprising him so that he had to steady himself on his feet. He'd shrunk; I was now a head taller than he. "Hello, my boy," he said, grinning and taking my upper arm in a firm grasp. "Shall we get out of here?"

"Sure, Dad." I slung my overnight bag on my shoulder, refusing the hand he stretched out for it. In the parking lot, I asked if he wanted me to drive, then regretted my request; he looked at me severely, humorously, and got his glasses out of the inside pocket of his sport jacket, wiping them with his handkerchief before putting them on. "When did you start driving with those?" I asked, to cover my gaffe.

"Oh, I was supposed to years ago, but I didn't really need them. Now it's a little easier with them on my nose, I'll admit." He started the engine, and we pulled magisterially out of the lot. I noticed that he drove more slowly than I remembered and that he sat peering forward; they were probably old glasses. It seemed to me that his stubbornness was one of the main characteristics he'd passed to his only child. It had preserved and strengthened us both, but had it also made loners of us?