L’appetit vient en mangeant.”

There are a few ways to translate that French adage about appetite. There is the straight sort, “Appetite comes with eating,” and the cynical sort, “The more you have, the more you want.” There is also one that has the loft of aphorism and the canniness found in almost everything the French say about food: “Appetite grows by what it feeds on.”

I believe that one. It comes to mind on what would have been Julia Child’s hundredth birthday, because she, whom I never met but whom I love, like most cooks and writers do, as I love things in nature—un-ownable and completely mine—wrote something that is true and important and is starting to seem as extinct as good amounts of fat in food: “Certainly one of the most important requirements for learning how to cook is that you also learn how to eat.”

That seems simple, or indulgent. I think it is deep and transgressive, and not in the way we figure culinary transgression today. To me, it quietly suggests something a little scary but also exciting: learning how to eat is engaging and joyous, useful—not holy, because in Julia’s world nothing was—but transformative, changing how one tastes and cooks.

We rarely think of learning to eat like that, and not doing so causes all sorts of dissonances where there could be—and where, in le monde Julia-enne, there would be—warbly, imperfect consonance.

We think of learning to eat in one of two ways.

The first is learning how to eat healthy food. This is treated as a necessary but bitter pill, judging by the apologetic looks that people give me when they explain that they’re trying to wean themselves off processed foods and fatty foods, to eat more salads and vegetables, and so on.

The other version of learning how to eat is gourmandism; today’s prevalent formulation appears to be deciding to squelch one’s conscience and philosophic systems—which for most of us, regardless of background, place high value on moderation and balance—in the interest of developing a taste for the finer things.

Julia learned how to eat. She did not preserve and shelter her plain, perfectly good Pasadena palate by moving to France and then cooking there, then writing books. She let herself taste and smell differently. She took seriously the smells and rhythms around her, and noticed how they changed her perception—and she came to like them.

That process was what started it all. It’s right there in the first pages of her memoir, and it’s at the heart of her mastering something enviable and unique, becoming someone who cooked well but not perfectly, whose tastes ran the gamut, and who didn’t make exceptions or put foods into categories according to what she was supposed to like but didn’t, or what was theoretically “good” but in some way “bad.”

We have all heard Julia say “I just hate health food,” and that diet food was what one ate while waiting for the steak. But she also said, in the same theoretical if not literal breath “You must have discipline to have fun.”

That is what it means to learn to eat. Few of us are encouraged to do as Julia did, and eat in a way that lets us be formed, neatened, honed; that lets us take on eating as a thing to learn, a path that may leave us, god forbid and god grant, tasting and thinking of things differently than we do now.

Other than that it’s Julia’s birthday and nice to talk about her, what does musing on learning to eat matter?

It matters a lot. It applies potently to curious eaters today, who look for guidance to restaurant kitchens, and to professional cooks and food writers, because a trend is developing in restaurants and cookbooks—one that sets up a false dichotomy between the kind of food that is “right” for chefs and line cooks to cook and the kind they “like” to eat.

It’s visible everywhere, most clearly in the perception that many chefs and cooks decide what to do at work with one part of their brain and then conceive of their own personal appetites with a different part.

We know—because we see everything that cooks do these days—that when cooks and chefs get off work they go eat greasy cheeseburgers and instant macaroni and cheese; that they call one thing “good,” when they season it and put it together for strangers and another thing “good” when they make it for themselves.

I think that if we all followed Julia’s counsel, there wouldn’t be a difference. And I think that it would far improve the meals professional cooks season and assemble for strangers, as well as the meals they eat off the clock.

It’s hard to make something truly wonderful if it’s not something you deeply love and long for. Theoretical ideals are a bugbear for a craftperson. They are hamstringing—imagine trying to make a good chair never having seen one, or write a melody without having heard one. But if you love clear flavors and teach yourself to taste them, if you love sweetness only in complexity—if you stick to a path with a sense of purpose, as Julia did, and allow your palate to ripen, then food being “good” becomes all of a piece.

That we have made it not of a piece has always perplexed me, because I learned how to eat on food that’s more like what Julia Child learned to eat on—as though eating were teething, or reading. I learned how to taste salt by eating it on tomatoes, learned to love butter thickly spread on thick bread, put in big pats into pureed soups at the last second, or spread on hot ears of corn or English peas.

What I long for, what I hunger for, deeply, lustily, and sensually, are those things.

I have met other people whom it perplexes, too. I sat and drank a lot of wine with the Alabama-based chef named Frank Stitt in Michigan, one night in May after cooking a meal, and we found ourselves talking about it.

“What do you like to eat?” he asked me. I love vegetables with a lot of olive oil and vinegar, I told him. I like braised beef, cold, with anchovies; pork belly, but not a lot, ideally with beans, buttery onions, and herbs. I love bread soup. I can like not much more than broth with an egg poached in it, or broth with spring garlic. I love all chicories and lettuce, as long as it’s young and fresh.

I asked him the same question. “I like to eat what I cook,” he said. “After a long service, I like a lot of lettuce, if it’s on the menu, or vegetables with vinaigrette. I love the food I make and make the food I love.”

That many cooks and chefs don’t feel the same way was underlined by an article in the New York Times last month. It was a long, silly thing about chefs trying to make their own ketchup but really liking Heinz, lining their cabinets with good nut butters but really preferring Skippy. It appealed to the dichotomy in which “trying to be good” is what cooks do at farmers’ markets, and “allowing yourself to be bad” is what they do, with gusto, at the grocery store.

Julia did not disdain much. She chortled and ignored more often, but I think that sort of thing would have her shaking her head.

I heard Frank’s take on this and my own, unarticulated one, in the documentary “Jiro Dreams of Sushi.” The chef of a sushi restaurant says, over what looks like a very good lunch of a few deliciously fried things and shiny noodles in a wicker basket, eaten by him and his kitchen staff: “In order to make delicious food, you must eat delicious food. The quality of ingredients is important, but you need to develop a palate capable of discerning good and bad. Without good taste, you can’t make good food. If your sense of taste is lower than that of the customers, how can you impress them?”

Appetite grows by what it feeds on.

That is to say, Julia Child would encourage doing away with the fuss of right and wrong, and really asking oneself to take seriously the job of becoming a committed and ecumenical taster, a liver of the life of the table.

Since my book on cooking came out, I am sometimes asked what my “guilty pleasure” is. I don’t know how to answer it well. (On a video taken by NPR I once panicked and said “peanuts,” though I have no idea what that means, and am existentially amused at the idea of having peanut-generated guilt.) I love to eat what I eat. My pleasure at the stove and table are sincere and coherent.

That is not because I’m good or rich, but because I listen to Julia, especially to another translation of hers, of the term “gourmand,” a word so often tinged itself with superiority or classism, or obsession. “Happy eater,” was how she used the term. I believe that one, too.

A former editor at Harper’s Magazine and cook at Chez Panisse, and the founding head chef of Farm 255, Tamar Adler is the author of “An Everlasting Meal: Cooking with Economy and Grace.”

Illustration by Tom Bachtell.