Last year when I took my daughter and her friend trick-or-treating, they approached a brightly lit house alive with energy. The two girls knocked on the door, but no one came. Instead a woman leaned out of the window of a small kitchen crowded with people preparing a dinner party.

"I'm sorry, we don't have any candy," she apologized as the guests behind her scrambled around the counter in search of a suitable offering. "But … hold on … " Milky Ways or no, they were determined to fulfill the age-old custom that when supplicants come to your door asking for food, you must give. She passed two pears from her fruit bowl through the window and dropped one into each girl's bag. Apologies were made and thank yous exchanged as both giver and receivers laughed.

Fruit is not quite the letter of the Halloween law. But on a night when the dead roam the earth, it's the spirit that matters.

Full disclosure: We were in Britain, where Halloween is still catching on — and the natives are grappling with their mixed feelings about this intrusive American import. But even there, enough people get that it's bad luck to turn away those who seek hospitality on your doorstep.

That's exactly what I love about Halloween. It's the one night of the year when complete strangers come to our homes asking to be fed and we deliver, even if it is usually in bite-sized morsels of factory-made chocolate. That exchange feeds the soul even more than the body, and right at the time of year when we otherwise close up our homes, shut out the cold world, and turn inward.

Long before Game of Thrones, Halloween was there to remind us that "winter is coming." In a world before a global food network, factory canning, and deep freezers, once the harvest was in, scarcity haunted the earth until spring planting. Which explains (in part) how we find Halloween's Celtic roots in Samhain, an "occasion of stock-taking and in-gathering, or reorganizing communities for the winter months," says historian Nicholas Rogers in Halloween: From Pagan Ritual to Party Night.

Like many autumn holidays, Halloween hangs at that crossroads of plenty and want, of loss and remembrance. It's a place where ghosts and food fraternize as we find ourselves simultaneously contemplating the seasonal death of the earth and the lives of our ancestors who have passed before us. Think Chuseok in Korea or Day of the Dead in Mexico. Or remember that this Hallowed Eve ushers in a trilogy that also includes All Saints' Day (November 1) and All Souls Day (November 2).

And yet it's not in the food offerings to our ancestors nor in the necessity of stocking up and hunkering down for winter, nor even in the centuries-old tradition of soliciting "soul cakes" from door to door that we find the backstory to our modern tricks and treats.

With all its airs of old folkways and seasonal food traditions, this peculiar practice we call trick-or-treating is a pretty recent — and a pretty commercial – invention. And it's how a rowdy anti-social holiday was transformed into a child-friendly, community-minded celebration.

Slashed tires, broken windows, street fires, petty theft. That's how revelers once made Halloween a night of terror. In 1958 a writer for the New York Times lamented the new tamer 31st and longed for the wild Jazz Age nights of the 1920s when "a cop was a cop and a kid was a kid and on Halloween each of them knew it." But in 1950, the United States Senate Judiciary Committee proposed that all that destructive Halloween aggression be transformed into a "Youth Honor Day." During Halloween that same year, the Parent and Child section of the Times encouraged "the community application" of a classic parenting technique: diversion.

How better to distract children than with the soothing pleasures of sugar? In 1953 the paper reported how the New York State Youth Commission encouraged adults to keep a steady "supply of cider and donuts" for children to "have fun without injury to property." By Halloween 1954, the Curtiss Candy Company promoted their Butterfingers and Baby Ruths with "complete sanitary protection, convenience in handling, cleanliness," while Kellogg's promoted their Snack-Paks of cereal as doorstep offerings. In 1959 Kool-Aid also ran trick-or-treat ads.

But even as trick-or-treating became a kind of role-play charity, children also took back the night to entreat celebrants to give to bigger causes. The 1950s launched the tradition of collecting money for UNICEF instead of candy. And in 1951 children in West Carthage, New York, went door to door asking for clothing, soap, and toothpaste for Korean refugee families in a "treats for overseas" campaign. Rogers notes that in the same decade Grosse Pointe Michigan children cried "help the poor" rather than "trick-or-treat" as they invaded neighbors' homes in Halloween costumes.

Any cultural anthropologist will tell you that "liminal spaces" like doorways are filled with symbolism and alive with the possibility of transformation. They are gateways between inside and outside, us and them, family and stranger. Places where opposites meet. Just like Halloween itself, which tradition says is the night when the veil between the dead and the living falls.

This year especially, with the sharp divisions of a bitter political climate, be ready to reach across the threshold and welcome strangers with sweetness, no matter what guise they may come in. It's called hospitality. And it won't come for another 364 days.

Happy Halloween!