Tunnel Under the World

Déja vu: as Guy Birkett goes through the day he has a nagging feeling that he's been here before, experienced this already; except the details are always different. Is it conceivable that he is merely a simulacrum, the ultimate in consumer market surveying? He finds there is a reality behind the reality he knows; but for a pawn to question the reality of the chessboard is a perilous undertaking.