(USA TODAY) -- Your Valentine's Day checklist probably includes chocolates, cards and a dozen red roses. So how did all this start?
USA TODAY Network looks at the origins of a few of our most popular Valentine's Day traditions.
Ironically, the day when we celebrate love may have much darker origins. Ancient Romans celebrated the feast of Lupercalia on Feb. 13-15. The feast involved animal sacrifices and whipping women, thought to make them more fertile, according to Noel Lenski, a historian at the University of Colorado-Boulder, in an interview with NPR.
But the first direct connection between St. Valentine's and the idea of love comes much later, in the poetry of Geoffrey Chaucer, says Andy Kelly, an English professor at the University of California-Los Angeles, who wrote the book Chaucer and the Cult of St. Valentine.
Chaucer, best known for The Canterbury Tales, wrote a poem called "Parliament of Foules (Fowls)" in 1381 to honor Richard II's engagement, Kelly said.
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In the poem, St. Valentine's Day is celebrated on May 3 - not Feb. 14 - and represents "the day when all the birds choose their mates for the year," Kelly told USA TODAY Network.
"Quickly afterwards, within a generation, people took the idea of celebrating of St. Valentine's as a day of love," Kelly said.
The St. Valentine whom Chaucer was probably referencing was St. Valentine of Genoa, who died on May 3 and whose feast day was celebrated on May 2, according to Kelly's book. But people at that time were not as familiar with St. Valentine of Genoa.
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Two St. Valentines - one of Rome and one of Terni - were martyred on Feb. 14, although in different years. The idea of St. Valentine and love became linked to this Feb. 14 date.
"The emphasis on the birds choosing mates for the year fell by the wayside because birds weren't around in February," Kelly said.
The British Museum in London has a Valentine dated from the 15th century, but it wasn't until the mid-19th century when Valentine-giving became popular in England, said Ann C. Colley, a distinguished professor of English at SUNY-Buffalo State.
Two things happened: First, England's first postal service, the Penny Post, was established, making delivering mail cheap and available to everyone, not just those who could afford it. Second, machines brought mass production of these cards.
Printers started developing different methods of printing, such as embossing, attaching lace and creating three-dimensional cards, said Dan Gifford, a professor of American history and popular culture at George Mason University and author of American Holiday Postcards: 1905-1915.
This "fad" of card-giving for Valentine's Day started in England but traveled to American culture as well in the 1840s, he said.
"The merchants, the printers, the stationers all pick up on this very quickly and put up big displays in the window," Gifford said.
It wasn't just lovers who received Valentine's cards. In England, some Valentine's cards were meant to be given to someone you didn't like.
"You don't sign these cards, and you could really get back at someone," Colley said.
Along this theme, there were also satiric political cards. "It would be equivalent if, in our country, the head of the Tea Party sent a Valentine to Obama," Colley said.
Chocolate has long been considered an aphrodisiac, said Alexandra Leaf, a culinary educator and founder of Chocolate Tours of New York City, in an interview with USA TODAY Network.
Starting in the 17th century, when cacao beans were first brought to Europe from Mexico and Central America, Europeans associated the food with stories about Montezuma and his many wives, Leaf said.
The 19th century was a "turning point" for making the sweets more affordable to the middle class with the mechanization of chocolate-making, Leaf said.
In 1861, Cadbury was the first chocolatier to offer chocolates in a heart-shaped box, according to the James Beard Foundation, a not-for-profit promoting the culinary arts.
"There's a carryover of the aphrodisiac notion that would make it appropriate for Valentine's Day," Leaf said.
The cherub-faced Cupid we recognize today was originally something quite different.
In the 5th century, the Greek version of Cupid, Eros (the inspiration for the word "erotic"), was depicted as a tall young man, who was "athletic, heroic and had wings," according to Angeline Chiu, associate professor of classics at the University of Vermont in an interview with USA TODAY Network.
The most famous story about Cupid comes in 8 A.D. from the Roman poet Ovid. In the story, Apollo tells Cupid to "leave archery to people like me," Chiu said. To prove Apollo wrong, Cupid shot Apollo with a golden arrow so he would fall in love. Cupid also shot a lead arrow at the nymph Daphne. Apollo falls in love with Daphne, but she is repulsed by him.
Meanwhile, "Cupid sits back and watches and laughs and laughs," Chiu said.
Chiu said Cupid's transformation into a baby can be credited to Renaissance art.
"Raphael and all those guys painted little, fat babies everywhere," she said. "They didn't always mean Cupid. Sometimes it was just generic love."
It's the image of Cupid as a cute baby with wings that has endured.
In the 18th century, Charles II of Sweden introduced the idea of flowers symbolizing emotions or messages carrying non-verbal messages, according to ProFlowers.com.
Today, red roses stand for passionate love, pink roses for friendship, white for purity, and both red and white mean unity, said Jennifer Sparks, spokeswoman for the Society of American Florists, in an e-mail to USA TODAY Network.
Yet, Sparks said people should not be too concerned about flower meanings, but instead focus on what type of flower the recipient likes.