"Lighten up!"

"Smile!"

"Things can't be that bad."

"Come on, cheer up."

To all those compassionate souls who issue such good-hearted injunctions to the obviously disheartened wherever they spot them, who thereby attempt to encourage high spirits whenever they seem to be failing, Miss Manners has a counter-exhortation:

Please cut it out. If you don't understand the situation, don't try to fix it.

Miss Manners appreciates general cheerfulness as much as anyone. She knows what it is to be impatient with people who glorify ordinary cases of what used to be called the blues into full-scale depression, which they believe entitles them to spread gloom wherever they go.

But unlike the free-lance emotional missionaries, of whom we seem to have quite a number now, she recognizes the legitimacy of somber moods and respects the privacy of strangers.

It is a noble undertaking to assist someone in grief by offering warmth, support and understanding. This is a service that one owes everyone one cares about, and that gifted and committed people are sometimes able to offer to a wider circle.

But it requires both time and sensitivity. There is no easy answer to tragedy.

The damage that even close friends can do when they dispense ill-thought-out comfort to those with troubles is inestimable. People who attempt to assuage grief by announcing, "It was all for the best" or "You'll get over it" or one of those funeral favorites, "You'll marry again" or "You'll have other children," are simply heaping on additional pain.

This is why we have conventional forms for offering consolation under nonintimate circumstances. These contain no advice, but only an expression of sympathy: "I'm so sorry," "I want you to know how much I feel for you," "You have my deepest sympathy." To offer advice if one does not know the person, even if one has experienced a similar situation, is foolhardy. To attempt to do so on a hit-and-run basis, with pat slogans, is arrogant to the point of rudeness.

Miss Manners was horrified to come across an anecdote by a prominent playwright in which he complained of detecting an unpleasant mood in an attractive stranger with whom he shared a table at a crowded eatery. He reported having taken her silence personally, but having triumphed over it with a sarcastic "Nice chatting with you."

The reply was "My best friend died today," to which his response was, not quite in genteel terms, that he hadn't killed her.

Humorously, he suggested that he liked to think that "my quick and elegant rejoinder raised that woman from the morass of her legitimate personal problems and mired her in mine."

Not generally immune to wit, Miss Manners failed to find this amusing.

Perhaps it was because something similar, although not quite so pointed, had happened to her. She was traveling on an airplane when a fellow passenger, noticing that she was dressed in black from head to toe, probably with a facial expression to match, cheerily remarked: "Hey, it can't be that bad. You look as if you've lost your best friend."

Possibly his motive was to spread good cheer. But as Miss Manners happened to be traveling to a funeral, he did not accomplish this. Not intruding her mood on anyone else, she was unpleasantly rattled to have anyone else intrude upon hers.

And an intrusion is exactly what this sort of thing is, however well-meant. It is also uniformly ineffective. No one ever cheered up as a result of being summarily ordered to do so.

I'm interested in American tendencies to say or do the wrong things abroad, because of our lack of knowledge about other countries' customs and manners. Could you please tell me some of our biggest mistakes when we travel to other nations?

Major Mistake No. 1: not inquiring what local customs are for showing respect, tipping, dressing, accepting what one is offered, issuing compliments, initiating social relationships, eating and drinking, showing gratitude to hosts, minding one's own business, and what time to show up in relation to the time stated on an invitation.

Major Mistake No. 2: pretending that one is thoroughly acquainted with local custom, and thereby forgoing the advantage of playing the dumb but well-meaning foreigner, whose inevitable errors of etiquette will be regarded as amusing and forgivable lapses rather than vulgar violations of known standards.

Is it proper to include the groom's parents' names on the wedding invitations? Our son was married more than a year ago, and our name was not on the invitation.

Traditionally, only the names of the bride's parents, in their capacity as hosts, go on the invitation. Miss Manners hopes you have not been nursing a grudge over this all year.