When Sean died she understood for the first time how completely human beings were dependent upon a suspension of disbelief in order to simply move forward through their days. If that suspension faltered, if you truly understood, even if only for a moment, that human beings were made of bones and blood that broke and sprayed with the slightest provocation, and that provocation was everywhere--in street curbs and dangling tree limbs, bicycles and pencils--well you would fly for the first nest in a tree, run flat-out for the first burrow you saw.