Scholar and Sculptor, Working Inside the Head and Out Peter Bulow holds clay sculptures of his wife, Amy, and son, Isaac. Some of his works, enlarged to life size, are now on display at the Heather Garden in Fort Tryon Park. Snapping open a violin case, Peter Bulow reveals a line of clay heads - fellow passengers from his subway rides, carved on the fly. They fit in the palm of the hand they were born in. This is the sketch work of a sculptor shaping at the speed of the A train as it rumbles from 59th Street to 125th Street. Here is a man wearing a cap inscribed Korean-Vietnam War Veterans, a roaring tiger stitched on the side. A 13-year-old girl on her way to a violin lesson. A macho guy with headphones. A woman with a fur collar who seemed at peace. A couple snuggling. A man, mouth agape, dozing and drooling. Others, wearing regal turbans and dreadlocks and polyester extensions. A dozen of these heads have been un-shrunk by Dr. Bulow, a psychiatrist, who has enlarged them to life-size or bigger, for an exhibition in Fort Tryon Park called Passing Glances. The heads are perched in stone settees that overlook the Heather Garden and the Hudson River. Near dusk one day this week, Dr. Bulow, who lives in the neighborhood, strolled through the garden with his wife, Amy Kail, a choreographer, and their son, Isaac, 18 months. Well, strolled might not be the right word: Isaac darted. "Before Isaac, I would go to the stone carving studio after work," Dr. Bulow said. I started doing these on the way to and from. It becomes an obsession after a while. Now he has made hundreds, packing them into odd socks and grocery bags, or pillowing them on the crushed velvet of the violin case. At 52, Dr. Bulow has enough identities to fill his own violin case. He is an artist and a psychiatrist, an immigrant and the son of survivors of the Holocaust, a researcher asking whether magnets can reboot the brain circuitry of a depressed mind, a clinician listening to rational despair and withering psychosis in the east Bronx, and a guy on the subway with a lump of clay in one hand and a small cutting tool in the other. Of all the people he has sketched in clay, few have noticed, and none of his subjects have objected. "One guy on a train attacked me, but I wasn't sculpting him," Dr. Bulow said. He was wearing Army fatigues and was in a wheelchair with an American flag sticking out of the back. For some reason, he thought the clay was plastic explosives. He eventually grabbed my hand and he stuffed some of it in his nose. Dr. Bulow was born in India, the only child of a Hungarian mother and a German father who had moved there briefly for work. Back in Berlin, his uncle Oscar took him to the zoo, and he made lions of clay. The family moved to the Far East Side of Manhattan. At the beach with a friend one day when he was 13, his buddy built a rippling, muscled sand figure. "I made a Holocaust survivor," he said. He started out at Queens College as a biology major, then swerved into art. Some years later, he discovered a medical scholars program at the University of Illinois at Urbana-Champagne, where he earned both a medical degree and a Master of Fine Arts. He wrote plays and built puppets to perform in them, presenting his mother in stone effigy as a child hiding from the Nazis. "It was a ton to move every time we performed," he said. The insufficiency of art, a truth wrung from his psychiatric practice, drives him. "I sit on the train sometimes," he said, "and wonder who are these people. I'm sure a lot are going through incredible struggles - maybe psychosis, maybe financial ruin, and you can't see it in the faces. You wonder, how do you really know things about a person? He cites William Blake: "The human mask is forged in iron." You don't really know anything about a person by looking at them, and yet there's something fascinating about trying to sculpt people or paint people. Ultimately, you can't do it. Even if I did the same person all my life, the same portrait over and over, I would never really get them. It's ungraspable. That's what's fascinating about it. From the garden walk, the Bulow heads watch over a ribbon of broad river and soaring cliffs, sprays of heather and ancient trees that are bent with age and alight with spring color. One glance becomes a link to eternity, a jolt to the system, and he feels it afresh on his train rides, clay in his hand and lives all around him. "It's amazing that we exist at all," he said.