So while I struggled to write the book of Valentino's life, trying to uncover the truths of his early years and to untangle the story of the SPLA and its effect on the people of southern Sudan, he and I were watching what we had thought impossible: a step-by-step re-enactment of the war he had fled, only this time in another region of his country. Thus far in Darfur, the government of Sudan has been allowed to kill about 250,000 of its citizens in almost precisely the same manner in which they killed the people of southern Sudan. Year after year, since war broke out in Darfur in 2003, the government of Sudan has been allowed to pursue identical policies of mayhem. And though President Bush, among others, has called the killing in Darfur a genocide, this has not yet spurred the international community to stop the killing.

My daughter was born in October 2005, and after a few weeks, I began to take her on walks in the woods and hills near our home. The jostling of the walks usually put her to sleep within 20 minutes or so, but before she fell asleep, it was fascinating to see how she would react to her surroundings. She shunned bright light, closing her eyes tight. When we would pass into the shadow of a stand of eucalyptus, she would open her eyes again, and seem to concentrate on trees and ferns. And always, three or four times during any walk, she would sigh, a sigh far bigger than seemed possible for such a tiny creature.

I had never heard that newborns knew how to sigh. I know of course that their sighs do not mean for them what they mean for us. At that time, I was still struggling with the overall structure of the book, which had yet to be figured out in any real way. I had 600 pages of disconnected passages, and no interior architecture. The book was overdue and my inability to frame it, combined with my sense of powerlessness over Darfur - the killing was escalating, the chaos at a high point - gave my daughter's tiny sigh an outsized significance. Even she knows, I would think, of our impotence. Even she knows that most of our compassion is like so much mist, fleeting and inconsequential.

One night in the middle of this malaise, I got an email from Valentino, who was still living in Atlanta. The subject heading was "A BAD DAY". He explained that he had been mugged in his home, by people he didn't know who had knocked on his door asking to use his cellphone. When I called him, and when we saw each other soon after in San Francisco, he was more distraught than I had ever seen him. "It's different," he explained. When he had been the target of militias, of Antonov bombers, of government troops, it had never been personal. Now there had been people in his apartment, one with a gun to his head, who truly seemed to despise him. There was an intimate aspect to the attack that was new to him, and was haunting him nightly. He wanted to leave Atlanta, to be away from the chaos of that and any other city.

He showed me the complaint card that the police had given him. It was a business card with a phone number on it. That was the extent of their worry about a gun to the head of an immigrant from Sudan. They would not, it was clear, be investigating the crime. We would walk in silence those days, Valentino and I, the baby sighing. We had no answers for anything.

It was at this time that I knew the book needed to be not only about Valentino's experiences in Sudan and the camps, but also about the many unforeseen struggles of his life in the US. The attack became the framing device for the book, and connected to something he had told me during our first weekend together. We had been talking about the small indignities he'd experienced taking the bus around Atlanta, trying to get to work. He had been pushed, ignored, disrespected. And each time he would think, silently, "If only that person knew what I'd already been through ..." He would direct his thoughts to whoever had treated him less than humanely, and hope for a day when his story was known far and wide, and that perhaps then his sufferings small and great would end.

This, in turn, connected with the creation myth that eventually became the title of the book. The book had originally been called It Was Just Boys Walking, then, for a while, Hello Children (after a textbook used in the camps), but soon those titles seemed inappropriate. Valentino had been a man for a long time now, and he and the other so-called Lost Boys were tired of being known as boys. The story of Valentino's life would need to be equally, if not more so, about the issues he faced today. We had agreed that we would include in the book an ancient creation myth known in southern Sudan. In the story, God, pleased with his greatest creation, offers the first Dinka man a choice of gifts: on the one hand, the cattle, visible and known, an animal that can feed and clothe him and last for ever; on the other hand, the What. The man asks God, "What is the What?", but God will not reveal the answer. The What was unknown; the What could be everything or nothing. The Dinka man does not hesitate for long. He chooses the cattle, and for thousands of years Dinka lore held that he had chosen correctly; the cow is thus sacred in southern Sudanese culture, the measure of a family's wealth and the giver of life.

It was not until the torment of the southern Sudanese in the 20th century that the Dinka began to question this choice. What was the What, they wondered, and speculation about the answer abounded: was it technology? Education? Sophisticated weapons? Whatever the answer, it was assumed that the Arabs of the north - who, legend had it, had received the What - might have got the greatest of God's gifts, and were using this What to inflict unending pain upon the southern Sudanese. Valentino and I had long thought the legend an apt expression for the themes of the book, and we planned to include the story in some way, but it was not until he was attacked in his home, amid the ongoing killing in Darfur, that this creation myth became the title of the book. It was clear then that not only did Valentino and the people of Sudan not know what the answer to the question was, but perhaps they weren't even asking the right questions.