It took a long time to figure out what was wrong with him (he was two before we had a clinical diagnosis) and how to keep him alive,  He belongs to the clan of human beings who were kept alive by medical technology, a group that comes with a new set of rules.

But even more pressing, to me, was the question of what his life meant, what significance it had, given that so much of it was lived on the periphery, in the twilight of the normal. Did he have an inner life? Did he have what some might call a soul? Did he have a contribution to make?

He seemed to, but he couldn't say. Between the stretches of darkness that constituted his often painful life, there were also brilliant flashes of light.  His complete joy, for instance, when he had the chance to dance for twenty seconds with his older sister in the living room.  His utter absorption when she read him a story, though it was also obvious he didn't understand a word. When we take a stroll down a busy city street in Toronto, where we live, I push his chair with my elbows while keeping up a steady stream of commentary on passersby. "Look, Walkie," I'll say, "the white miniskirt seems to be back big time this summer." Or: "That same side of beef has been hanging in the Hungarian butcher's for two years. Remind me not to eat there."

I'm sure he doesn't understand what I'm saying, but being on the receiving end of my chatter makes him laugh like a mad man. He may not be able to take part in a conversation, but he apparently likes to be treated as if he can. It thrills him, and makes him happy, and so it makes me happy too. This is one of the ways we spend time together.

So I decided to write about him.

I decided to tell the story of his life, as he presented it to me, from what I could see, from what I could infer, often based on sheer speculation.

I try always to write about him with respect but honestly, because he is honest (he has no choice to be otherwise).

He is never sentimental, and so neither am I when I write about him.

I try to be funny when I can, because he has a robust sense of humor. (One of the strange pleasures of life with Walker is trying to figure out what he finds so hilarious, and why.)

I try to be grave or serious as well, because he is, most of the time. Mostly I try not to write anything I would not want him to read, if he could read.

For my troubles, I have been criticized by strict disability advocates for telling his story without his permission.

"Who gave you Walker's consent to tell his story?" one critic asked.

The answer, obviously, is: I did. There was no one else to give it. I'm his father, but I'm also his surrogate in the world of consciousness, his agent of action.  Not that I'm the only one.  But if his story is as telling, as significant, as it sometimes feels, it has to be written down. Otherwise it ends up untold, along with all the other untold stories. Better to put it on paper, than not.

I'm not saying I do any of this without getting pretty nervous. I brace myself for the task by remembering a story I once heard about Agnes de Mille, the famous American choreographer of Oklahoma and Brigadoon and Rodeo!, to name just a few of her many creations.

De Mille was an enormously successful choreographer and dancer, but she had her moments of doubt. She once asked Martha Graham (about whom de Mille wrote an biography) how she could know if her art was worth anything.

Martha Graham replied that it wasn't Agnes's job as an artist to question the value of her work. All she had to do was "keep the channel open," and turn what came out of it into an expression of what she wanted to say.

Walker was born with his channel closed. Someone has to open it, and keep it open. That's why I write about him--because he will be completely voiceless otherwise. And that would be an even greater shame than any offence I may give to people with standards that are stricter than life can afford.