“What’s our motto? Use your words: ‘You can’t always get what you want,’” my wife says. She’s talking to our seven-year-old son, J., who’s having a meltdown in the back of the car. We’re thirty minutes from home, which seems, under the circumstances, like an unbearably long time.

My son’s tantrum started when he asked for a chocolate ice-cream cone and my wife said he’d have to wait until after dinner. It escalated from there. Now, there’s no telling what will set him off, what will bring on the tears and screaming, the kicking and whining. The whining is the worst; it’s so unrelenting I catch myself in awe of the sheer force of will required to sustain it. “I’m mad; I’m not mad. I am; I’m not,” my son says, launching into a self-contradictory soliloquy, during which he’ll agree to nothing, not even how he feels.

J. is also autistic, though I’m never sure if I’m supposed to mention this--use it as an excuse for his behaviour. This may be one of those instances when he’s acting like any kid would who’s not getting his way. Sometimes, it’s hard to distinguish. Other times, not. At least, it no longer is for us.

Four years ago, when my son was diagnosed with autism, I looked up the word in the dictionary. “A mental disorder ... characterized by self-absorption,” it said, and I remember thinking, for an instant, that sounds like me. Then: That sounds like everyone. I know better now. I know the look in my son’s eye, the sound of his voice when he’s gone somewhere else, somewhere deep and secure inside himself. I know why his tantrums have become, in the last year, so fierce, his frustration so unfathomable. Because he wants to get back there and we won’t let him. Everything we do is designed to prevent him from doing what he most wants to.

On the broad spectrum of autistic disorders, J. is high-functioning. The first psychiatrist to evaluate him concluded he had “a whiff of autism.” I nearly hugged her; the phrase sounded so quaint.

A whiff? What’s a whiff? Nothing. Barely noticeable. Like a mole, a lisp. Like being left-handed.

It would take a while to realize she was just doing what experts invariably do when they’re trying to explain a disorder as enigmatic, as unpredictable as autism; they tell you what you want to hear and hustle you out the door. Any parent of an autistic child knows there’s no such thing as “a whiff of autism.” While it’s true there are kids worse off than J., that does not make the gulf between my son and the world he has to work so hard to engage with any narrower. It does not keep that gulf from growing wider every day.

“Motto?” my wife continues, holding up Forty Licks, a compilation of Rolling Stones hits we keep in the car. My son, who’s finally catching his breath, uses his words. “Number six,” he says, “‘You Can’t Always Get What You Want.’” J. is not a child for whom logic will ever be simple, but somehow the simple logic of Mick Jagger’s line appeals to him. That’s why we need to be careful not to overuse it, my wife says. It’s a feature of autism that anything that begins as if it’s going to be a good thing--like an interest in music--is bound to turn bad.

So she saves the song for moments of crisis or those moments of crisis we can no longer deal with. Another thing I’ve learned about having an autistic child: everything is a crisis.

My wife and I both avoid using the A-word, though we refrain for different reasons. My wife because she believes, down deep, that, with hours and hours of behavioural therapy, luck, dedication, determination, and a positive attitude, autism is something J. will overcome or at least battle to some kind of uneasy but workable truce. That’s why she prefers I not use his name here: because she believes that J.--a mostly sweet, affectionate boy, who makes eye contact, talks, reads, writes, and, with a shadow, goes to a regular school--will one day be indistinguishable from any ordinary kid.

I don’t use the A-word because I believe, down deep, that this will not happen. I’m afraid that whatever progress my son makes is not going to be enough. By which I mean--and am deeply ashamed to admit--enough for me. When our son was diagnosed, my wife dealt with the devastating news by springing into action, developing a game plan, networking, badgering government agencies, hiring help, borrowing and begging money, holding out hope. To-do lists still litter the house: under fridge magnets, on Post-it Notes, and pads by the telephone.

My plan of action, when I learned about our son’s autism, was to sulk. I spend what’s left of my time debilitated by envy--watching family, friends, strangers interact with their children. And, oh yes, I sigh often, not loudly--just loud enough for my wife to hear.

Usually, she ignores me, which is, as she knows, the best strategy for dealing with J. or me, when all we really seek is attention. But this time, perhaps because I’m driving and sighing at the same time, because she knows how easily my mind wanders to dark places, she pats me on the back and says, “One in five.” The reference is to a statistic she read recently in a newsletter for the parents of autistic children. Evidently, eighty percent of husbands with an autistic child leave--walk out on their marriage and family. This is her way of reinforcing my good behaviour, of telling me what I want to hear. That, under the circumstances, I’m doing well. Better than most.

My wife never completes the chorus to “You Can’t Always Get What You Want.” She never goes on to the lyric about how “if you try, you get what you need.” She knows J. wouldn’t understand, though come to think of it, who would? Who ever does? Want is easy, after all. Want is unambiguous. It knows no reason; accepts no excuses. It wants what it wants. Want is ice cream before dinner. Want is everything the way you expected it. It’s your son ordinary, just ordinary. Our family motto, it turns out, doesn’t suit either my son or me. What do we want? We want precisely what we are not permitted to have.

Need is something else entirely; need is trickier. It’s about coping, making do. What can I get by with? What bargain can I strike? What do I need? The minimum? I need to grow up.

“Please, Daddy, number three?” J. says, holding up Forty Licks, making a calm request from the back seat. “We’re almost home,” my wife says, but she relents, tired, finally, of being the only adult in the car. Number three is “Satisfaction”: more tantrum than tune, Jagger in a rawer mood, less mature, more demanding. I glance at my son’s happy face in the rear-view mirror as he sings along, and, before “Satisfaction” comes to an end, we’re home.