We complain about having faulty memories. Whoever these people are (they look familiar, but after a while everybody does, so it's best just to nod pleasantly), they seem to recall that they had excellent memories when they were young.

So do today's youths, who could remember everything if only they would start paying attention and taking responsibility. But try asking them where you left your glasses and see if they have the faintest idea.

It is worrisome to Miss Manners that spotty memories can create etiquette trouble. Motivation is supposed to count when judging possible rudeness, and she is hard-pressed to think what evil intent could cause people to forget to mail letters or where the car is parked. Nevertheless, it sure does make everyone testy--the forgetters no less so than those they inconvenience--and the next move from either is not likely to meet any standard of politeness.

It would seem, then, that a good memory has a beneficial effect on manners, which explains why people value it. Even Miss Manners only listens to the excuse of having forgotten a social engagement if it is accompanied by repeated smiting of the forehead against the floor.

By way of consolation, she would like to point out that too good a memory has a detrimental effect on manners. There are an awful lot of things that a polite person is obliged to forget, and it is difficult to keep them all in mind. So here is a partial list of Things to Forget:

Slights committed more than a month ago.

How fond you were of a possession that a horror-struck guest just broke.

Earlier versions of stories your parents tell you about family history.

The childhood nicknames of people you meet again as adults.

That you were just as much or more in love with someone else before your current commitment.

Anybody's IQ or SAT scores you happen to have heard, whether they are high or low, beginning with your own.

Facts relating to an incident being related by someone else in the family, which, however relevant to the story, render it pointless.

Minor grievances committed more than a year ago.

Anything unflattering about someone whose wedding or funeral you are attending, even if the person in question used to think it was glamorous or funny.

That you broke rules that you expect your children to follow and suffered no adverse consequences.

Any joke that anyone has already started to tell.

What it was like to harbor notions that are detrimental to your children, such as feeling that being popular is the most important thing in the world.

That you warned your child not to marry the person he or she is now divorcing.

Legitimate grievances that happened more than 20 years ago.

That you made a total fool of yourself, unless you have repackaged it into a funny story and are no longer haunted by it in the middle of the night.

Is that all? Miss Manners can't help thinking that there must have been other things on the list.

(c) 1999, Judith Martin