I have a younger brother who is going to change the world. His name is Joshua, after the U2 album. He is twelve years old.

Some summers I look after him, while his parents are away working and another of my brothers, much more gregarious, is at camp. Joshua is an introvert and an incorrigible bookworm. He reads more things than almost anyone else that I know: any novel he can lay hands on, encyclopaedic tomes about nature and the universe, the fine print on the backs of lift tickets at ski resorts, software manuals, public service announcement pamphlets about changes in sewage treatment policy. He can remember even the tiniest details from them later on. His schoolmates are afraid of him, mostly. For a long time I was his only friend.

The summer he was eight sticks in my mind the most. All of July and August we hung around the house playing card games during long afternoons and reading books from the library, and stargazing at night. He knew more constellations than I did but was patient with me and explained their significance.

"That one there is Scorpio," he would say, and then wait until he was sure that I had found it in the sky before moving on, "and that one is Saggitarius," and then the rest of the zodiac, or at least the ones we could see from our west Edmonton rooftop. We didn't go inside until well after it had gotten too cold for comfort.

Later on he asked me what I was going to be when I grew up. I said I didn't know -- it was true then, and still is, mostly. I asked him the same thing and he said, very seriously, "I'm going to be an astronaut." I believe him.

He asked me for a story before bed and I told him that I'm not very good at stories, at least not ones with happy endings; maybe he could take a turn and tell me a story instead?

"Okay," he said, "How about, when I'm grown up I'm going to be the guy who is in charge of terraforming Mars. When it's done it will be like the Earth, only with no pollution and we won't bring any mean people along because they ruin everything." I nodded and remembered how he had come home from school one day with bruises all over and a black eye and bloodied nose and wouldn't tell anyone what had happened. "But there will be sharks there just in case," he added, "so if someone turned out to be bad after all we could feed them to the sharks. Sharks with laser beams on their heads."

Eight-year-olds should not watch Austin Powers movies, let alone be able to quote them back at you. Lest the conversation stray into more questionable territory I asked, "Would you live there forever, or would you come back someday?"

He thought, hard. I was about to tell him that I would understand completely if he didn't want to come back when he looked up from his thinking and said, "Yeah, I'd come back. If I didn't I would miss you guys too much. Besides, space gets lonely sometimes, with nobody to talk to. Sharks don't say very much."

I thought, Here is a kid who knows all about lonely and hurt, and he would still rather be here than be nowhere.

"When would you come back?" I asked.

"For Christmas, probably. Maybe birthdays too, but they would need me on Mars. Besides, re-entry into the Earth's atmosphere is always pretty dangerous. So is landing. That's why they land in the ocean, with parachutes to slow them down first."

"Well, it'd be nice to see you," I said, "so long as you're careful coming back."

"I'm always careful," he said, then reached to turn off the light. "I think I'm going to sleep now, okay? Good night."

Maybe this is what grace is, this being able to love even when you're misunderstood, being patient with other people even when hardly anyone ever returns the favour. I've changed my mind since then; when I grow up I want to be like that. I wish I could think half the things that my brother can.