It’s customary on St. Valentine’s Day to write odes, buy chocolates, and lavish romance upon the burning object of one’s affection. Approximately 140 million Valentine’s Day cards will be exchanged on the holiday, estimates suggest.

But why do we do all these things?

Most people, it’s safe to say, undertake these tasks without an inkling of who Saint Valentine was or how the traditions actually began. They can be forgiven, however, because there is a great deal of uncertainty surrounding Saint Valentine and the holiday we celebrate in his name. Here’s what we know.

The history of the Saint Valentine (176-273 A.D.) is hazy and legends vary. Stories center on a third-century Christian priest named Valentinus who defied the Roman emperor Claudius II—either for ignoring a law forbidding the marrying of Christians or for concealing persecuted Christians—and was sentenced to die. One legend has it that while he was imprisoned Valentinus was moved by the faith of a blind girl, and on the eve of his punishment (stoning followed by decapitation) he wrote her a touching adieu, signing it “From your Valentinus.”

Later, in 498 A.D., February 14 was declared “Saint Valentine’s Day” by Pope Gelasius. That date could have been selected to commemorate the day Valentinus was martyred. Other theories suggest that Gelasius selected the date to co-opt Lupercalia, a popular Roman holiday that centered on pagan rituals that involved animal sacrifice, nudity, and the whipping of females. (It was one big pagan party. The Roman romantics “were drunk. They were naked,” Noel Lenski, a historian at Yale, told NPR.)

Did it really happen this way? Not necessarily.

Jack P. Oruch, an English Professor at the University of Kansas who died in 2013, believed all of these theories were rubbish. Oruch became convinced the English poet Geoffrey Chaucer was the inspiration for our modern conception of St. Valentine. He wrote a long article about it in 1981 (“St. Valentine, Chaucer, and Spring in February”) but later implied that nothing could dislodge the popular ideas that had formed around the holiday.

“All the articles about Valentine’s Day each year repeat the same myths,” Oruch said in 2011.

So who is right? I have no idea. I suspect, however, that the New York Times had it right in 1851 when the paper asserted that St. Valentine’s Day “is one of those mysterious historical or antiquarian problems which are doomed never to be solved…”