In less than three days the old apothegm is substantiated in short sequences which cover anything from late arrivals to their mitbrings- the brightly wrapped problem package, the child who gets sick, even pets. Then there's a good deal about healthy relaxation -- like a sunburn, or other amusements, summer theatre, volleyball, birdwalking; or beds, breakfasts, guest room reading where ""Zhivago is the doctor in attendance""; etc., etc. Recognizable moments of discomfort or discomfiture provide some casual, occasional humor which will be supplemented by the 26 drawings by James Stevenson, New Yorker cartoonist and novelist. Need we say for whom or when?