Marion Ettlinger, celebrated for her pictures of authors, forbids her subjects to smile for their portraits. ”If one is going for an iconic moment, one shouldn’t smile.” Most art photographers assume that the smile is a mask that must be removed. Why Canada, expressly prohibits any traces of a smile in a passport photograph.

But on the other side of the aisle, Jean Jacques Rousseau wrote that ”Accent is the soul of a language; it gives feeling and truth to it.” He might have also said that facial expressions – in particular smiles – give feeling and truth to talk.

In Far From the Madding Crowd, the spirited heroine Bathsheba is faced with a choice of three men. Only one of the suitors, Gabriel Oak, has an authentic smile:

When Farmer Oak smiled, the corners of his mouth spread till they were within an unimportant distance of his ears, his eyes were reduced to mere chinks, and diverging wrinkles appeared around them, extending upon his countenance like the rays in a rudimentary sketch of the rising sun.

Of course Bathsheba ends up making the wrong choice. Had she been more astute she would have seen in Oak’s smile something more than cachet or capital. (Listen to me. I’m writing as though I think I am Jani Allan). Another intense smile was described by Charles Dickens in this way: “In came Mrs Fezzywig, one vast substantial smile.” Then there is  this:

He smiled, understandingly – much more than understandingly. It was one of those rare smiles with a quality of eternal reassurance in it, that you may come across four or five times in life. It faced – or seemed to face – the whole external world for an instant, and then concentrated on you with an irresistible prejudice in your favour. It understood you just so far are you wanted to be understood, believed in you as you would like to believe in yourself, and assured you that it had precisely the impression of you that, at your best, you hoped to convey.

Scott Fitzgerald describing Nick Carraway describing Jay Gatsby’s smile.

There are people whose high intensity smiles are their trademark. Louis Armstrong, Ray Charles, Julia Roberts, Miss America runners-up (the winner always cries in faux disbelief), the Cheshire cat.

According to parapsychologist (there’s a concept!) Gary Schwartz and his colleagues, voluntary smiles are on average ten times bigger than spontaneous smiles. So although a smile may be a mile wide, it may be only a millimeter deep. This week I went through the ritual humiliation of having my eyes tested. “I want you to rest your chin here and tell me what you see,” says the eye wallah. “ASBF!” I exclaim triumphantly. “Now?” “DBLT!” Still triumphant. “What about this?” “B….er…looks like F – no P! Its P…and could be…. Now its the eye doctor’s turn to be triumphant. He give me a smile like the curve of a knife.

There are air hostess smiles, dental nurse smiles, politician’s smiles and undertaker’s smiles.

Voluntary smiles – such as servers are expected to generate – should be large. Their point is to be seen. If you want someone’s approval, a smile is as good a place to start as any. Getting the size of the smile right is a delicate calculation. Psychologists call this the ingratiator’s dilemma: how do you create a positive impression without giving the impression that you are wanting to create a positive impression?

Smile timing is important too. How long should you smile and when is it time for the smile to disappear?

What about smiles that appear attentive but are really merely sentinels behind which the wearer is cultivating their own thoughts. These smiles are deployed by those who are emotionally absent.

One of the most arduous things about my grilling life is learning how to smile appropriately.

There is the “Welcome I am your server….yadayada…” smile. Then there is the “Of course I will get you more bread/butter/ice smile. Then there is the cancer patient laughing at the doctor’s joke smile that you give a patron who left you with a paltry tip.

This week I mentally compiled an entire glossary of smiles. It was Lobster Week at the resto. For a ridiculously low prix fixe, diners were given mussels, lobster, chicken, sausage, corn on the cob, Red bliss potatoes and peach pie.

As I carefully placed the dishes in front of a couple, the woman gave me a smile that was not really a smile so much as a tool of inquiry. “Vot I must do vith zees” she queried. I mimed cracking gestures and spoke to her as we all speak to foreigners. “Take claw. Crack open. Eat this way. Delicious. Me gusta. I bring finger bowls” I explained. (“Me gusta” is the go-to Spanish phrase which should be used in all tricky situations.) I tried to give her a trustworthy smile. Her partner looked at me with facial disinterest. If smiles are indeed interpersonal velcro, this one wasn’t it. Mostly a server is rewarded with a smile that is like a half-opened tin can. Sometimes the smile can be warm as a Tuscan sun shimmering across a valley of vines. Occasionally we are treated to a formidable smile, which displays the teeth and the whole personality. Once I was given the sort of smile memories are not made of as much as repaired by.

I have to report that the most insulting smile you can give a server is one that is flashed like a torn photograph. This is especially effective when the wife doesn’t bother to look up at you while you are (pretend) smiling and thanking them. Great Spirit, grant that I may not criticize my customer until I have walked a mile in her Christian Louboutins.