On one level, this is a perfect epigraph because the whole novel shows how many other people intersect with one person's life and fate, each with his or her own perspective, and that one person may not even fully realize their influence. On another level, MacNeice's use of "plural" can refer just to that single soul, in this case Daniel, who is actively struggling to bring all of his disparate parts and connections into one whole-hearted being. In many ways he has been holding back in his relationships, shattered by guilt and grief. His need to find out about Nicola is really his need to begin dealing with all that, which he's buried for so long. And sadly for him, he can't talk about it, leaving Claudette to give rein to her own demons, and separate from him-- despite still loving him--which just fragments his life even more. And when he falls completely to pieces, due to more losses, more guilt and grief, what helps him find his way out, into the wholeness he seeks, is the "plural," his children and his chance encounter with another person he barely knows, but whose influence is all-important. Like Daniel, every person's sense of self, of identity, is made up of many personae or roles that we have played throughout our personal relationships, and if the "inside is not the same as the outside," as Pascaline observed of Daniel, that is a clue that we haven't fully integrated our fragments into a whole that we can live with.