“It didn't help when he told David that his mother would always be with him, even if he couldn't see her. An unseen mother couldn't go for long walks with you on summer evenings, drawing the names of trees and flowers from her seemingly infinite knowledge of nature; or help you with your homework, the familiar scent of her in your nostrils as she leaned in to correct a misspelling or puzzle over the meaning of an unfamiliar poem; or read with you on cold Sunday afternoons when the fire.”