“When you got right down to the place where the cheese binds, there was no such thing as marriage, no such thing as union - 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 air-liner 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 tread lightly, if you valued your marriage and your peace of mind; you tried to remember that anger at such discovery was the province of fools who really believed it was possible for one mind to really know another.”