It's a reassuring illusion to believe that we know where we're going and what will happen along the way. But who has not encountered the Big Event, the unplanned occurrence that forever changed our little plans and schemes?

It became like that for every thinking person when, in 1905, a flash of insight led Albert Einstein to the Theory of Relativity. We thought we understood the universe, and then we saw we didn't.

It must have been like that for Einstein himself, too. He can't have awakened that day and decided that he would revolutionize the accepted tenets of physical existence. It just came, and his life was different forever.

It might also have been like that for Michael Paterniti, the young Maine writer who has produced "Driving Mr. Albert." It is hard to imagine that his life's plan listed the day he would hear about a guy who owned Einstein's brain, find him through incredible happenstance, learn after befriending him that he had business out West, offer to drive him and his cargo, and then write a book about the trek.

But that is what happened, and as with Einstein's theory - sort of, though only in a relative way - we are all beneficiaries. "Driving Mr. Albert" is entertaining, absurd, real, weird, deep, informative, silly, and slightly overdone. Above all, though, in a world in which it seems that all the good ideas have been taken, it is singular.

At the center of this tale is the inscrutable Dr. Thomas Stoltz Harvey, the 84-year-old keeper of the brain. The doctor doesn't talk very much, and often is unresponsive when he does. Once when given an A or B choice, for example, his answer is, "Oh sure, that would be nice." Given a second chance, the reply is "Way-ell, read good." He comes across as a genial enigma who leaves plenty of space in between his lines that Paterniti seeks to fill, not always credibly, with his own suppositions.

When Paterniti found him, Harvey was working an extruding machine in a plastics factory. But in 1955, Harvey was chief pathologist at Princeton (N.J.) Hospital, where Einstein had gone to die. Harvey was a last-minute substitution to do the autopsy, a change that would alter his life forever.

When Harvey came to the great thinker's brain, he removed it almost on a whim and took it home, intending to study it for clues to Einstein's genius. Ownership of the organ became a public issue, and Harvey eventually lost his job - though not the brain - over it. As the years passed, no studies resulted, and eventually, Harvey melted back into obscurity.

It's all part of the enigma: If there were no studies done, did Harvey just have some ghoulish curiosity, or what? Paterniti leaves it to readers to decide Harvey's motivation, and answers will vary. But it seems safe to suggest that Harvey will be judged more lightly than Dr. Henry Abrams, Einstein's ophthalmologist, who removed Einstein's eyes. "They were part of the brain, too, and I wanted a keepsake," he told Paterniti.

It's an outrageous comment that would seem too over the top if it weren't true, a sensation the recurs throughout "Driving Mr. Albert." Another example of it is how Paterniti became a part of the story. He thought the tale of someone having Einstein's brain was just an urban myth, and he was telling it as such to his landlord one day when the fellow said, "Yeah, the guy with the brain lives next to William in Lawrence, Kan."

What are the chances of that, paying rent to a guy who knew the guy who lived near the guy? Infinitesimal, right? But it gets better: What are the chances that the "William" of the story is William Burroughs, the Beat writer? Outrageous, and yet routine.

Such juicy details are a writer's dream, but "Driving Mr. Albert" is more than a rote retelling. Each of Paterniti's choices for layovers along the route brings with it new hilarity, or frivolity, or oddity. Their visit with Burroughs, for example, is worthwhile just for this Burroughs line, addressed to Harvey: "What keeps the old alive, Dr. Senegal, is that we learn to be evil."

While piloting their rented Buick Skylark, Paterniti never loses sight of the basic absurdity of driving cross-country with a brain in the back. He has to suppress the persistent impulse to blurt out - in drive-throughs, for example - "We have Einstein's brains in the trunk!"

When they arrive in Las Vegas (can you say "Rain Man"?), he feels the need to mingle, but takes it on the chin when he leads with the brain: "I'm traveling with the doctor who owns Einstein's brain, and we're going to California to give it to Einstein's granddaughter," he tells an elderly couple, who flee the table in the next instant. It's "weirdly empowering," Paterniti writes, "this sudden ability to repel people." Before long, he's been barred from the casino. Despite a relationship that grows over months, Harvey never appears to think of Paterniti as more than his chauffeur. Paterniti has seen the brain only once, in a dingy safe-house, but on the trip, Harvey deflects Paterniti's entreaties to get a better look. At first it's just rankling, but it becomes maddening when he returns from their first moments apart, a short break to do laundry at the New Mexico home of Paterniti's best friends, and learns that Harvey had shown it to them!

"Driving Mr. Albert" has few jangling pieces, but one of them is Paterniti's love story, which is either overblown or poorly established. More than once, he voices the fear that his wife, writer Sara Corbett, won't be there when he gets back. But even upon rereading the setup, there seems to be no reason for the worry beyond an attempt at melodrama. Even so, his cleverness shines when, at the end of a phone call in which he and Corbett haven't particularly connected, he vivifies a phrase one hears all the time: "Please hang up and try again." Much of his play with the language is similarly successful, though when he calls Einstein "the original cosmic slacker," it's hard to understand what he's talking about.

Paterniti relates early on that this won't be his first grand sojourn; he has up and left everything behind more than once, a habit that may explain his fears for his relationship. What it certainly explains is his keen awareness of the transformative nature of travel, "those moments in transit when you ride in the bubble of your own thoughts."

Those transformations, of course, come in all sizes, often commensurate with the reach of the trek, whether it is an 11-day sprint across America or our traverses through the universe.

SIDEBAR:

HAPPY WE'LL BE

Harvey isn't without a sense of humor, though it's dry and highly sporadic. In fact, waiting for it is like waiting for a cuckoo to appear on the hour - and realizing that, with this particular clock, the cuckoo only arrives once every six or seven. When Harvey locates what's called the Salt Fork of the Arkansas River on the map, he deadpans, "Way-ell, I wonder where they keep the Pepper Fork?"

Rolling with the Ogallala aquifer somewhere under our wheels, and huge cow-uddered clouds overhead, we gain a new appreciation for each other. On the radio: steer calves and heifers for sale, Red Angus bulls, yearlings with good genetics and a quality carcass. And then Bobby Darin singing "Beyond the Sea." Harvey taps a finger on his knee, the brain sloshes in its Tupperware. Beyond the dashboard, the earth unfurls - miles of browned grass and foam. In this happy moment, we could probably drive forever. By twilight, there's a nocturne of warm rain on the roof of the Skylark. We pass a pungent nitrogen plant, itself like a twisted metallic brain. Then a momentary moon through the clouds. Water towers gleam in the silver light like spaceships, telephone poles pass like crucifixes, and grain elevators rise like organ pipes from the plains.