“I consider myself an enlightened man, Cousinniece. I am aware that, as often as not, things just happen for no reason beyond the mechanics of their happening. A man slips on the ice and falls off a cliff. Why? Ultimately, because of the laws of friction and gravity. Intermediately, because he was wearing the wrong shoes for conditions, or put his foot in the wrong place, or was stupid enough to be walking on ice near a cliff in the first place. I know that! And if what happened to Hilary had been an isolated thing, if you and your family hadn’t lost her and I hadn’t lost Allyson in a different way, and …”

“Everything that happened afterward,” she had finished for him. “The string of disasters. More than our fair share. We’re back to that Original Sin idea, and that family history you’re putting together.…”

“You are doing that now,” he reminded her. “It’s your baby. Do whatever you want with it, including nothing. As for myself, maybe I had hoped that bringing certain things out into the sunlight—and sunlight’s the best disinfectant—would be an expiation in and of itself.”

And so she had assumed from him the roles of family historian and etiologist, seeking to trace cause and effect, searching amid the sins of the fathers for the one great sin that might explain to her satisfaction why her sister had to die, senselessly, at the age of twenty. This has not been her sole occupation for the past six years. She breeds and trains reining horses on San Gabriel ranch: 160 acres of grass meadow and oak and juniper uplands more than twenty miles by dirt road from Nogales, on the Mexican border. The ranch keeps her busy all day, but there is nothing to do at night in such an isolated and lonely place, and rather than drink or sit up watching her satellite TV, she pores through the trove of stuff she got from Myles, from the trunks and boxes at Mingulay, from the Williams family, and from a Boston genealogist, a man named Buckmayer.

Sybil began with the fragmentary tale her mother told her. Willynilly, she found herself re-creating the voyage, inventing things, not out of whole cloth but out of the threads in the logbook. I don’t believe that she has the power to see into her family’s past, as she claims she does; but I’m not going to make fun of her or deny that it’s at least theoretically possible to possess a kind of extraordinary genetic memory that can be summoned up from time to time. At any rate, she has tried to resurrect that summer in Nathaniel’s, Eliot’s, and her grandfather’s early lives as it probably was lived. She says I should consider her story an exhibit in the natural history of her family. She has taken shards of authentic bone, fossil ribs and partial mandibles and broken joints of fact, and fused them back together with fabrications to create a whole thing. That is what she has been after all this time—the creation of a whole thing, with what art she commands, and there is truth in art.