The title of this book is no accident. The implication of the title is that the nostalgia one feels for their childhood is like the frustration mankind faced when they were rejected from the garden of their paradise, Eden. This basic mythological connection between paradise lost and childhood identities lost are essentially the same, and for Nell, that really does take the shape of a full-blown existential process.
But much like Moses doesn't quite reach the promised land, neither does Nell, and it's her granddaughter Cassandra who finishes the hero's quest toward identity. This makes Nell a sacrifice, her life given so that her daughter and her daughter's daughter would have a head start on the difficult journey toward understanding oneself.
This addresses the intergenerational nature of human narrative quite poetically, showing the strange way that all stories interconnect, and showing that in a weird way, although it's not what people mean by "eternal life," there is a sense in which Nell's legacy is shaped by the journey of her children, embodied in them.
