Michael J. Fox, television and movie star, has walked his share of red carpets over the years. These days, though, he walks a more nondescript bit of floor covering: a cheap sisal mat in the garage of his Aquinnah house. Pacing, back and forth, doing laps of the pool table trying to harness the involuntary energy of his illness. Hours upon hours of pacing.

"I wish I had an odometer on the miles I've walked on this rug," said Mr. Fox, who at 46 retains, 15 years after being diagnosed with Parkinson's, his boyish good looks and apparently boundless optimism and good humor.

It's a pretty spartan environment in the garage; there are no memorabilia of celebrity. There's an old, falling-apart rocking chair in which he sometimes rocks. There's a refrigerator stocked with water and soft drinks, a card table and an old wooden desk.

This is where Mr. Fox largely wrote his first book, Lucky Man, documenting his career and his experience with Parkinson's disease, which, nine years after diagnosis in 1991, forced the end of his full-time acting career. He did not physically write the book - the words were all his, there was no ghost writer - but someone else transcribed it.

"I just basically paced this little strip right here - we're in my pacing zone right now - and I'd just speak it out," he said.

His assistant, Heidi Pollack, would type his spoken words on the computer, then print out and he would edit. "And we would do that just endlessly until we had something I felt I could send to my publisher," he said.

The book was a roaring success and spent seven weeks at the top of The New York Times bestseller list. It drew rave reviews for its warmth, its uplifting message and its wry humor and it generated a couple of million dollars for the foundation Mr. Fox set up to fund research into Parkinson's.

And now, five years after Lucky Man came out, he's doing it again. Pacing the old rug, dictating to a new assistant, Asher Spiller. The title of this second book will be Always Looking Up, a reference not only to his optimism, but his stature. "It's a short joke," he said.

Why the second book?

"The thing that people responded to so much in the first book," he said, "was the hopefulness that I have, and it's only been strengthened by my experience since. And I started to look at various areas of my life, whether it was business or politics or family or love or relationships, all these areas of my life where my hopefulness and my optimism was the guiding principle, was what motivated me forward and helped me through."

A great deal has happened since Lucky Man - perhaps most notably Mr. Fox's run-in with right-wing demagoguery during the 2006 mid-term elections. But more on that later. First, the back story.

Mr. Fox was only about 30 when he began experiencing symptoms of Parkinson's - often considered an old person's disease - and was enjoying a highly successful acting career. His two hit television series, Family Ties and Spin City, won four Emmys and Four Golden Globes between them. Spin City also landed two Screen Actors Guild awards. And there were movies, too, including the now-classic Back to the Future trilogy. Remarkably, for seven years after his diagnosis, he managed to keep his condition a secret, not just acting in roles, but acting like he did not have a debilitating illness.

He went public in 1998 and stopped acting full time in 2000, although he has since done some guest appearances and voice parts for animated films, notably as the voice of Stuart Little in that movie trilogy.

Then in 2002 came the book. And if the title at first blush appears somewhat ironic - it wasn't.

He explained: "I once said to somebody that in a way it [the Parkinson's] was a gift. And they called me on it. And I said ‘Well, you know, it's a gift that keeps on taking.' But in a way it is a gift because it really taught me acceptance. It taught me a lot about taking life on life's terms. And it opened up a way for me to be of service that I hadn't imagined before . . . the opportunity to start a foundation which to this point has put about $100 million into research. That's nothing short of a privilege. It's just a real honor. I realized as I talked to people I used expressions like lucky and gift and whatnot, and that could take some explanation. And so in my late thirties I found myself writing a memoir."

Up until he got the disease, he had to an extent squandered his good fortune. Having grown up in Canada in a family with neither show business background nor any great means, he got so much so fast he couldn't quite handle it.

"My father was in the military and my mom was a payroll clerk," he said. "To find myself in the situation I was in was like ‘How did I slip in here? I don't deserve this.' My feeling was like someone was going to come knock at the door at any moment and say, ‘Okay we made a mistake; give it all back.' And I was just determined that when they did, I was going to be drunk . . ."

Then the party boy started noticing small tremors which could not be attributed to drink.

"I was experiencing things like a twitch in my pinky and weakness on my left side, which I didn't know were symptoms of early onset," he said.

He put off having it checked out. It was while staying at his home on the Vineyard (his wife Tracy has been coming here all her life and first brought Michael here on their honeymoon 19 years ago), that he realized there was something seriously wrong.

"I was jogging along Moshup Trail - actually, coming down Lobsterville Road - and Tracy came out because it was taking longer than it usually did to do that circuit. And she saw me and she said, ‘You know you're not moving your left side as you run. And I said, ‘Yeah it felt kind of funny, kind of labored.'"

He went to the doctor.

"I went in and I was diagnosed and I was shocked and angry at the doctor for doing nothing more than his job. You know you have that first instinct of, ‘Do you have any idea who you're talking to?' Like that makes some kind of difference."

Then he took to his bed.

"It was like, ‘I have Parkinson's. I can't carry those groceries in. I have to lie down.' And that lasted for like two days and then I went, ‘What the hell is this? This is stupid.'"

He set about reordering his life. He stopped drinking, realized the importance of his family - he has four children, 18, 12 (twins) and 5 - and the relative unimportance of his career. Now, he said: "Every moment is a moment of discovery as I figure out what the next thing is, what the next opportunity is. That's why I feel lucky.

"The luck was not in the diagnosis, not in the acquisition of the disease; the luck was in the circumstances in being able to deal with it, and the outcome of certain processes it put me through."

His second book is scheduled for completion next April, and will be out in time for the 2008 Presidential election. On the day of the interview, as thunder rolled overhead, he was working, appropriately, on the section dealing with the storm which broke over him during the 2006 mid-term elections.

It happened like this. Mr. Fox had done a series of advertisements supporting candidates who also supported stem cell research. His agenda was not partisan - one ad supported Pennsylvania Republican Sen. Arlen Specter's 2004 campaign - but his intervention in the tight race angered some conservatives.

The strongest attack came from talk show host Rush Limbaugh, who accused Mr. Fox of either deliberately going off his medication or acting worse than he was, calling him shameless.

Far from being upset by the attack, Mr. Fox found the circumstances fantastic. He recalled he laughed.

"I was like, ‘He really said that? He really would allow himself to be on television making fun of Parkinson's symptoms? Wow, let's see where this goes.'

"Our goal was to educate voters about the stem cell issue and what was there to be accomplished and what had been forsaken with the current policy, but the nature of the counterattack was such that it opened up a whole secondary conversation which was about the level of discourse in political matters and other matters of social importance. The attack was so ad hominem it was jarring to people."

It was jarring to Mr. Fox's mother, who called him immediately she heard about the Limbaugh attack.

"She was so livid, she was like a little Irish teapot, she was like, steaming. I was calming her down about it saying don't worry about it. It is what it is. We told the truth."

Even Mr. Limbaugh had to accept in the end that Mr. Fox was not faking, once a few facts about Parkinson's were explained. Key among them: the manifestations of the disease are highly variable, both between individuals and within individual cases. Mr. Fox said they can change every second of every day. And while people think the symptom of Parkinson's is a tremor, the ultimate symptom is a paucity of movement. The lack of dopamine, the brain chemical which fires the neurons which make you move, eventually becomes such that you freeze up. As a result, managing movement is a constant juggling act with medication. A little too much medication brings on dyskinesia, the characteristic rocking and dipping. But it is a price to pay for being able to articulate clearly.

"Limbaugh's first attack was that I was faking the symptoms. Then, short of that, that I didn't take my medication, as if that's some kind of responsibility I have not to scare people," he said, adding:

"That was the first issue. When we answered that, he [Limbaugh] apologized in his kind of half-assed way, but then his next move was, ‘Well, this was a show for the Democrats.'

"So we said the record will show we've been pretty consistent. If a candidate in whatever race is pro-stem cell, and is running against a candidate who is anti-stem cell, it doesn't matter to us which party he belongs to. The evidence is in the fact that we've done ads for Arlen Specter previously. So there went that argument." He continued:

"It was a dream come true for us. "What could have been a one or two-day story about the fact that we shot these ads, because of what he did, became a two-week story. And we found ourselves, two days before the election, with an hour of prime time on CNN, talking about stem cells."

Come the next election, will he do similar ads?

"Absolutely," he said.

"Our mission is to let people know it's not just an abstract issue, it's real. We've wasted eight years when we could have progressed," he said.

But politics are not the whole focus of the new book. It will touch on science too, but mostly it will be, like the last one, about coping with what life throws up. It's what his readers want.

"People come up to you and talk about it. They ask you questions that you don't know the answer to. The only thing you can do is sit down and ask yourself the questions and that ends up being a book," he said.

There is plenty to write about - Parkinson's is an idiopathic condition; everybody gets their own version, he said. No two people respond the same way to the array of drugs; everyone has their own cocktail. And everyone has their own progression and combination of symptoms.

"There's no standard chart to measure yourself against," he said. "I'm 17 years out from diagnosis, so definitely there has been a deterioration of certain abilities and certain processes."

"But I am so not clinically depressed that it's kind of jarring. Especially here on the Vineyard - I go to the beach every day when I'm not writing. I go golfing. Later in the summer I play a lot of tennis and play hockey in the winter."

The slow progression of his illness is probably due to his relative youth at diagnosis - Parkinson's tends to advance more rapidly with age. Medicine can treat the symptoms, but it can no more retard the disease than it can cure it.

"By the time you are diagnosed, by the time you have your first symptoms - they say at that point 80 per cent of your dopamine-producing cells are already dead," Mr. Fox said.

"Another thing that our foundation has been trying to do is find a biomarker and a way to diagnose, to predict the disease so that we can treat it prophylactically and maybe find things that will retard the progress of the disease.

"Strictly speaking, nobody dies from Parkinson's disease, but everybody who has Parkinson's disease dies with Parkinson's disease. The only certainty right now, at the current state of medicine is that I'm going to die with it."

His delivery of prognosis is matter of fact with no hint of self-pity. Indeed, true to his nature and book titles, Mr. Fox qualified himself, with emphasis.

"That's the certainty to this point. We're hoping to change that," he said, concluding:

"This is my life and I'll take it and I'm grateful for it and I don't want another one."