Drawn on the tablecloth

In a small Moroccan restaurant in Paris, a guest who has never eaten the food asks what a dish on the menu is, and two people on the floor give two kinds of answer.

The first says it is a traditional tagine with preserved lemon and olives. Every word is accurate. The guest is no wiser, because each of those words was already on the menu. The question has been answered with the label it came with.

The second tries something else. Think of a chicken you might roast at home, she says, but cooked slowly in a closed pot so that it comes apart with a fork. The lemon has been kept in salt for weeks, so it tastes less like a lemon and more like something between a lemon and an olive. Then she picks up a pen and draws the pot on the paper cover of the table, the tall lid and the way the steam runs back down into the food. The guest orders it.

The difference is not charm. The second person understands the dish. She knows what it does and why, and so she can move it from one form into another: into a comparison, into a picture, into terms that belong to the guest rather than to the kitchen.

That is the real test of knowing something. Not whether you can repeat the words that usually go with it, but whether you can carry the idea across into a different shape and have it arrive intact.

Most explanations that fail are not badly delivered. They are given by people who had the vocabulary and not the thing, which is why the sketch on the tablecloth is so rare, and so persuasive.