He more than half suspected that one of the things which had kept their marriage together when it seemed as if each year brought the news that two or three of their friends’ marriages had collapsed was their respect of the mystery – the half-grasped but never spoken idea that maybe, when you got right down to the place where the cheese binds, there was no such thing as marriage, no such thing as union, that each soul stood alone and ultimately defied rationality. That was the mystery. And no matter how well you thought you knew your partner, you occasionally ran into blank walls or fell into pits. And sometimes (rarely, thank God) you ran into a full-fledged pocket of alien strangeness, something like the clear-air turbulence that can buffet an airliner for no reason at all. An attitude or belief which you had never suspected, one so peculiar (at least to you) that it seemed nearly psychotic. And then you trod lightly, if you valued your marriage and your peace of mind; you tried to remember that anger at such a discovery was the province of fools who really believed it was possible for one mind to know another.