As a young child, Daniel Tammet had seizures. They turned him into a strange boy.
''I'm seeing things in my head like little sparks firing off,'' Mr. Tammet, a 26-year-old Englishman, says tonight on ''Brainman,'' on the Science Channel. ''And it's not until the very last moment that those sparks tell me what on earth they mean.''
Sounds spooky, right? And to be sure, if the sparks told Mr. Tammet that he had a message for the bats, or that his hair was lonely, he might have come across as just another delusional solipsist. But Mr. Tammet's sparks are mightier than the usual sparks: They give him not bat-words, but pi to the 22,500th place and the capacity to learn whole languages in a week. He's not only a savant but also a warm and communicative man; he has the ability, rare in savants, to describe how his esoteric knowledge visits him.
After reeling off the answers to warm-up questions -- say, what's 37 to the 4th power? -- Mr. Tammet fields inquiries about the way he pokes the table while he's coming up with answers (1,874,161, say).
''I'm seeing the numbers,'' he explains. ''But I'm not seeing them. It's strange. I'm seeing pictures, shapes and patterns. Almost like a square, like the texture of water. Drops -- ripples, almost. Like something reflective. It's something you can look through, almost metallic. Like bubbles. Then a bit like a flash.''
Good luck boosting your learning power by trying to replicate this process. The documentary does not explain Mr. Tammet's methods, which he maintains are simply more revelation than calculation. But something in the way that Mr. Tammet describes the beautiful, aching, hallucinatory process of arriving at his answers illuminates the excitement of all cogitation. The film takes an enthusiastic, fascinated approach to savantism that gives viewers what we want: the chance to enjoy the spectacle of great intelligence.
One of nine children, Mr. Tammet grew up counting numbers in hopscotch and studying leaves. Here he tells Dr. Simon Baron-Cohen -- an autism researcher and a cousin of Sacha Baron Cohen, television's Ali G -- bullies ''didn't know how to tease me'' because he had enough social skills to get by. So they left him to his studies, and eventually he started learning languages, memorizing things and delighting people with the huge calculations he could do in his head. Mr. Baron-Cohen concludes that his autistic symptoms are not interfering with his life.
Mr. Tammet meets Kim Peek, the American savant on whom Dustin Hoffman's character in ''Rain Man'' was based. They hit it off, with Mr. Peek telling Mr. Tammet, ''One day you'll be as great as I am.''
The documentary also subjects Mr. Tammet to a series of tests intended to amaze viewers and convince scientists that he's not, somehow, cheating. When, after only a week of language study, he appears on Icelandic television, chatting in the native tongue like a pro, the skeptics appear to be silenced. Part of what Mr. Tammet tells his interviewers is how beautiful Icelandic is. This does not appear to be mere courtesy. For Mr. Tammet, beauty is a significant component of thinking. In the most affecting scene in the documentary, he dreamily describes the aesthetic merits of numerals.
The number 1 he's drawn to for its brightness. ''Two is kind of like a movement, right to left, kind of like a drifting,'' he says. Five is a clap of thunder or the sound of a wave hitting a rock. Six ''is actually the number I find hardest to experience,'' he says. ''It's like a hole, or a chasm. Number 9 is the biggest number. It's very tall.'' He seems frightened for an instant. ''It can be intimidating.''
Later in the film, Mr. Tammet visits New York City, where he stands -- dutifully, for the cameras -- in Times Square. We've been told that Mr. Tammet, who is remarkably well adjusted, nonetheless dislikes flashing lights and noise.
He does seem to be facing some kind of sublimity, though it's apparently not the crowds or the Broadway street life that excites him. ''The number 9 is all around me,'' he says.