“He could swear he did not look back, could not—by any optical chance, or in any prism—have seen her physically as he walked away; and yet, with dreadful distinction, he retained forever a composite picture of her standing where he left her. The picture—which penetrated him, through an eye in the back of his head, through his vitreous spinal canal, and could never be lived down, never—consisted of a selection and blend of such random images and expressions of hers that had affected him with a pang of intolerable remorse at various moments in the past.”