I've always been fascinated by "idiots savant" -- people who are, for instance, lightning calculators, or able to tell you, the instant they hear your birth date, what day of the week that was. That's the savant part.

But the "idiot" part means that often these remarkable super-abilities are coupled with disabilities. No doubt some folks with super-abilities learn to hide them. It may also be that such abilities are linked to accidents of biochemistry, and thus are coupled with various kinds of physical or mental impairments.

Whichever the case, savants often have trouble communicating with the rest of us.

For instance, take Kim Peek, one of the real life models upon whom the movie "Rain Man" was loosely built. Peek was born with a water blister inside his skull. It damaged the side of his brain that handles language. Doctors predicted that he would never be able to walk or learn. One doctor offered to lobotomize him, the better to accommodate institutionalization.

In 1988, other doctors did a brain scan. Peek had no corpus calossum, the membrane or nerve cluster connecting the two sides of the brain.

But he learned to read at 16 months. In fact, he can read two pages at the same time -- one with each eye. And he remembers everything.

However, were it not for a dedicated father, Kim would have trouble negotiating the complex social rules that come easily to most of us.

I've just finished an autobiography of another savant. The book is called, "Born on a Blue Day," by Daniel Tammet. Like Peek, Tammet is autistic -- but it's a kind of autism (Ausperger's) that allows Tammet to function very well, although it takes some effort for him. Tammet has a host of savant abilities.

He can talk about them.

He is also "synesthetic." This means that his experience of senses is intermingled. Tammet begins his story this way: "I was born on January 31, 1979 -- a Wednesday. I know it was a Wednesday, because the date is blue in my mind and Wednesdays are always blue, like the number 9 or the sound of loud voices arguing."

Tammet is also a "power multiplier." Give him two numbers, such as 53 and 131, and they form distinct shapes in his mind. Immediately, he sees another shape that precisely fits between them. That shape is the number 6943.

Tammet achieved some fame recently when, as a fundraiser for an epilepsy foundation (Tammet also suffered from epilepsy as a child), he memorized 22,514 values to the right of the decimal point of pi. He recited them without flaw to an audience.

How? Easy. He just visualized the rich, colorful landscape numbers paint in him, no more complicated (for him!) than recalling some interesting houses along a favorite street.

Yet another of his talents is languages. Once, for a documentary, a TV crew followed him around for a week as he tackled a new language -- Icelandic. And at the end of a week, he was interviewed ... speaking Icelandic.

Epilepsy. Autism. Synesthesia.

Lightning calculation. Prodigious memory. The gift of tongues.

Tammet's story continues. But at present, life is good. He has found love (another man), and a career (web-based language instruction, available at www.optimnem.co.uk).

Finally, Tammet's tale provides a rare glimpse into growing up different.