From "Foreword to the Poems":
"This uneasy consciousness of lying is why in the great majority of novels the novelist apes reality so assiduously; and it is why giving the game away--making the lie, the fictitiousness of the process, explicit in the text--has become such a feature of the contemporary novel. Committed to invention, to people who never existed, to events that never happened, the novelist want either to sound 'true' or to come clean."
In many of his writings and interviews, Fowles has referred to fiction as a "game," one played between the author and reader. I think here he's suggesting two ways the author can play the game: either pretend as hard as you can that you're not playing a game, or invite the reader in on the game with you. Fowles, of course, chooses the latter. And that's something I've always appreciated about Fowles' novels. He's aware that he's playing games, but he's not trying to pull one over on the reader, treating the reader like a dupe. In The French Lieutenant's Woman, the author often speaks to the contemporary reader as a partner: his intrusions don't read as if the author and reader are facing each other, but as if author and reader are standing together facing the same direction. In both The French Lieutenant's Woman and The Magus, Fowles practically insists that the reader consider his or her reading experience, in a way that I would call "meta-reading."