oliver sacks is ogling my cough-drops. It's a damp, altogether dreary morning in mid-December, and when he spies me pulling a small sack of Fisherman's Friends from my pocket — I've just gotten over a bout with the flu. He asks, "Might I have one of those? They're quite addictive, aren't they?" For the rest of the interview he smacks away happily on several of the small lozenges, as content as a child with a lollipop. There's an unstudied, childlike quality about Oliver Sacks that, in person, is enormously appealing. He wears tremendously mismatched outfits ("I have no clothes sense," he explains), greeting a visitor to his spacious Greenwich Village office in black trousers, a blue checked shirt that's haphazardly tucked-in, a bright red tie and gray running shoes. He pops up enthusiastically every minute or so to show a visitor an artifact, or a map, or an unusual plant — as if the mementos of his life as the world's most peripatetic neurologist were in fact wonderful toys. Which, of course, they are. And he confesses that he eats the same things each day for breakfast and lunch (cereal with bananas) and dinner (fish with rice). He seems happy, alert, eternally curious.

Sacks' curiosity and compassion have led him to become one of the world's most rewarding writers about science, medicine and the vicissitudes of the human experience. His seven books — which include "The Man Who Mistook His Wife for a Hat," "Awakenings" and "An Anthropologist on Mars" — are largely case studies of patients with neurological dysfunction. Yet they are also potent — and oddly charming — meditations on what he has called "the wonder and horror which lurk behind life."

Sacks' new book, "The Island of the Colorblind," is a series of essays about his experiences in the Pacific Islands, including the isolated island of Pingelap, where a disproportionate number of natives have been born almost completely colorblind. (The book includes information about The Achromatopsia Network, a group that maintains a Web site devoted to sharing information about this kind of colorblindness.) Other essays in the book deal with Sacks' lifelong love of botany, and about how a favorite variety of cycad tree may have been responsible for a crippling disease on a separate Pacific island. "The Island of the Colorblind" is quintessential Sacks — a compelling blend of case studies, medical and natural history and offhanded personal observation.

Sacks, 63, is a lifelong bachelor. He continues to practice neurology and is Clinical Professor of Neurology at the Albert Einstein College of Medicine. He lives on City Island in the Bronx, where he raises ferns and cycads, and swims nearly every day, except in winter, in Long Island Sound. Because he seemed so intent, during our interview, on switching attention away from himself and onto various objects around him, I began by asking him what it was like, during his research for "The Island of the Colorblind," to have a film crew poking cameras in his face.

While you were researching your new book in the Pacific Islands, you had a BBC documentary film crew following you around. Did that alter your experience there?

Somewhat — both positively and negatively. My usual contact with people is quiet and intimate and often very prolonged. I stutter and I stammer and I come back the next day as a sort of postscript, as a follow-up visit. The pen and notebook are my tools. So I did feel somewhat put off at first by the cameras. And so did the others. But on the other hand, the filming was so discreet that after a while one would forget.

Next: Star Trek, the Grateful Dead and Tupperware.