"Sometimes watching him is like looking at the man in the moon — but you know there is actually no man there. But if Walker is so insubstantial, why does he feel so important? What is he trying to show me?"

Walker Brown was born with Cardiofaciocutaneous Syndrome, a genetic mutation so rare that doctors call it an "orphan syndrome." A teenager, he weighs less than 70 pounds. He cannot speak or feed himself. He is believed to function at the level of a two-year-old. His is a devastating syndrome that afflicts only about 300 people in the world, but that has touched the lives of many more.

A lot of that is thanks to Ian Brown's memoir, The Boy in the Moon: A Father's Search for His Disabled Son. It's an incredibly touching work that centres around how much a life — and especially a severely physically and intellectually disabled life — is worth.

As those who read his column in the Globe and Mail know, Brown is no stranger to writing about his personal life. The depth of his honesty here, however, is arresting. Life with Walker is something Brown has said he felt compelled to write about. He started keeping notes about it shortly after Walker was born, to help him understand what the experience was all about.

The meaning of Walker's life and the source of the feeling of importance or profundity behind it are things that Brown is careful not to trivialize by placing in a rigid box. Rather, he focuses on what he has learned about himself.

"He taught me not to be afraid," Brown said in an interview on Q. "He taught me not to conform, to say what you have to say and be who you are."

The Boy in the Moon has been awarded the B.C. National Award for Canadian non-fiction, the Charles Taylor Prize for literary non-fiction and, most recently, Ontario's Trillium Book Award.

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Watch Ian Brown being interview on The National.