You think you know the definition of pie. After all, is any dish more firmly ingrained in the American mind than a freshly made apple pie? Coming up with a workable definition of the dish should be as easy as - well, you get the idea.

But write out your best definition and those concrete images begin to crumble like a poorly made crust. Try this one: pie features a sweet or savory filling in a crust baked in a circular pan. What could possibly go wrong?

Get ready. If pie needs only a bottom crust, what's the difference between a pie and a tart? What about pot pies, which have only a top crust? Do hand pies count? Can you call it a pie if it uses a graham cracker crust? And what of shepherd's pie, which forgoes traditional crust for mashed potatoes?

The more I looked into the question, the more confused I became. I reached out to three pie mavens I hoped could clear up the matter.

Paula Haney, owner of Hoosier Mama Pie Co. in Chicago and author of The Hoosier Mama Book of Pie, takes a hard line, believing that pie must have a traditional pie dough crust. "I'm kind of a snot when it comes to pie," says Haney. "It comes from spending a lot of hours making and rolling dough. If you want to call it a pie, you better spend some time on it."

This ultimately means even some of the items Haney calls pie in her own shop don't meet her strict definition. Though she likes the flavor of crumb-shell crusts, like the kind used for a graham-cracker crust, she thinks they are "more like a candy bar than a pie."

Haney also believes seasonality is important: "Pie started as a way of preserving or utilizing what you had on hand. I think it would be best if it was kept to what is in season." Though Haney would love to more strictly follow that rule, she admits "there would be a riot" if apple pie were removed from the menu during the winter.

Kate McDermott, author of the recently released cookbook Art of the Pie, agrees that pie started as a filling completely enclosed in dough, though that was done less for taste, and more for food-storage purposes: "It was like the original Tupperware. Fillings were baked into a very sturdy flour-and-water base so it could help preserve it." This dense cover was referred to as a "coffin" in medieval England, if that gives you any sense of how the crust tasted.

The idea that the crust needs to encase the filling is one that a few fanatical voices make. A small group in England launched a government petition to make it a "criminal offence" to describe any dish as pie without both a top and bottom crust. That, of course, would exclude such American pie classics as pumpkin pie, sweet potato pie, key lime pie, all cream pies, and many more. I'd say most Americans wouldn't hear of such nonsense.

Maybe we should celebrate pie's incredible versatility rather than worry about creating exacting standards for it. In food scholar Harold McGee's On Food and Cooking, he writes that pie has "less to do with doughs than with odds and ends; it came from magpie, a bird with variegated coloring that collects miscellaneous objects for its nest."

"I don't think there is one answer," says McDermott. "Pie represents so much to so many people."

Ken Haedrich, the self-proclaimed dean of thePieAcademy.com and author of Dinner Pies released last year, thinks the question misses the point: "The fact that pie is generally accepted to be most any sweet or savory concoction, with one or two crusts, and baked in a pie or similar pan is perhaps the least compelling thing about it."

For Haedrich, pie has powers far beyond any strict definition: "Pie is memories, pie brings us together, and when people gather around pie, political differences tend to fade away."

This feel-good answer appeals to McDermott too: "There's tradition under that crust. I have rolling pins that have helped make over a thousand pies. It's impossible not to think of all those pies that have come before."

The Quintessential Apple Pie

Makes 8 servings

EndTextStartText

For the perfect dough:

21/2 cups flour

2 tablespoons sugar

1 teaspoon salt

11 tablespoons chilled unsalted butter, cut into small pieces

7 tablespoons chilled vegetable shortening or lard

4 to 5 tablespoons ice water

For the filling:

10 cups apples (skin on), preferably from 6 to 8 different kinds of apples, quartered, cored

1/2 cup sugar

1/2 teaspoon salt

1 teaspoon ground cinnamon

2 gratings nutmeg

1/2 teaspoon ground allspice

1 tablespoon apple cider vinegar

1 to 2 tablespoons Calvados or apple liqueur, optional

1/2 cup flour

2 tablespoons butter, cut into small pieces

1 egg white mixed with 1 tablespoon water

1 to 2 teaspoons (4 to 8 grams) sugar

EndTextStartText

1. To begin preparing the pie dough, pulse flour, sugar, and salt in a food processor fitted with a metal blade until combined. Scatter butter pieces over flour mixture; pulse about 5 times. Add shortening or lard; process until butter pieces are no larger than small peas and flour resembles coarse cornmeal, about 4 pulses. (This step also can be done using a pastry blender.) Sprinkle 4 tablespoons of the water over flour mixture; pulse 5 or 6 times. Add 1 teaspoon water at a time until dough holds together easily. Do not let dough form into a ball in the processor. Place dough on counter. Shape into ball with hands; divide in half. Flatten into two 1-inch thick discs. Wrap each in plastic. Refrigerate 30-60 minutes.

2. Cut the apples into chunks you can easily fit in your mouth. In a large bowl, mix apples with sugar, salt, cinnamon, nutmeg, allspice, vinegar, Calvados, and flour. Stir until mixture begins to look sandy.

3. Roll out 1 disc of the pie dough; use it to line a 9-inch deep-dish pie pan. Pour in apple mixture. Distribute the pieces of butter evenly on top. Roll out the top crust; place over the filling. Cut at least 5 vents in the top. Remove any dough that hangs over the side of the pie pan. Crimp the edges.

4. Cover pie in plastic wrap and transfer to fridge for about 30 minutes. Meanwhile, heat oven to 425 degrees.

5. Remove wrap from the pie. Brush the top of the pie with the egg white and water mixture. Transfer pie to middle rack in the oven. Cook, 20 minutes. Reduce heat to 375 degrees. Bake, 30 minutes.

6. Sprinkle sugar on pie. Continue cooking until evenly browned on top, and liquid just starts to bubble from vents, about 10 minutes. Remove and let pie cool for at least an hour.

- Dough adapted from Cook's Illustrated Magazine;

Filling recipe adapted from Art of the Pie (Countryman Press, $35).

Per serving: 570 calories, 6 grams protein, 71 grams carbohydrates, 31 grams sugar, 30 grams fat, 50 milligrams cholesterol, 448 milligrams sodium, 5 grams dietary fiber.