It's nearly impossible to go through December without seeing at least one nativity scene, whether it's a set of ceramic figurines in a private home, a life-size tableau in front of a church, or a cast of actors in a children's pageant. And rarely does a year go by that these representations of Jesus, Joseph, Mary, the three wise men, some shepherds, and miscellaneous barn animals go unmolested by vandals or unchallenged by lawsuits. Why do people put up creches at Christmastime, anyway?

Blame St. Francis of Assisi, who is credited with staging the first nativity scene in 1223. The only historical account we have of Francis' nativity scene comes from "The Life of St. Francis of Assisi," by St. Bonaventure, a Franciscan monk who was born five years before Francis' death. According to Bonaventure's biography, St. Francis got permission from Pope Honorious III to set up a manger with hay and two live animals — an ox and a donkey — in a cave in the Italian village of Grecio. He then invited the villagers to come gaze upon the scene while he preached about "the babe of Bethlehem." (Francis was supposedly so overcome by emotion that he couldn't say "Jesus.") Bonaventure also claims that the hay used by Francis miraculously acquired the power to cure local cattle diseases and pestilences.

While this part of Bonaventure's story is dubious, it's clear that nativity scenes had enormous popular appeal. Francis' display came in the middle of a period when mystery or miracle plays were a popular form of entertainment and education for European laypeople. These plays, originally performed in churches and later performed in town squares, re-enacted Bible stories in vernacular languages. Since church services at the time were performed only in Latin, which few understood, miracle plays were the only way for laypeople to learn scripture. Francis' nativity scene used the same method of visual display to help locals understand and emotionally engage with Christianity.

Within a couple centuries of Francis' inaugural display, nativity scenes had spread throughout Europe. It's unclear from Bonaventure's account whether Francis used people or figures to stand in for Jesus, Mary and Joseph, or if the spectators just used their imagination, but later nativity scenes included both tableaux vivants and dioramas, and the cast of characters gradually expanded to include not only the happy couple and the infant, but sometimes entire villages. The familiar cast of characters we see today — the three wise men and the shepherds — aren't biblically accurate. Of the four gospels in the New Testament, only Matthew and Luke describe Jesus' birth, the former focusing on the story of the wise men's trek to see the infant king, the latter recounting the shepherds' visit to the manger where Jesus was born. Nowhere in the Bible do the shepherds and wise men appear together, and nowhere in the Bible are donkeys, oxen, cattle or other domesticated animals mentioned in conjunction with Jesus' birth. But early nativity scenes took their cues more from religious art than from scripture.

After the reformation, creches became more associated with southern Europe (where Catholicism was still prevalent), while Christmas trees were the northern European decoration of choice (since Protestantism — and evergreens — thrived there). As nativity scenes spread, different regions began to take on different artistic features and characters. For example, the "santon" figurines manufactured in Provence in France are made of terra cotta and include a wide range of villagers. In the Catalonia region of Spain, a figure known as the "caganer" — a young boy in the act of defecating — shows up in most nativity scenes. In 20th- and 21st-century America, nativity figurines became associated with kitsch rather than piety, with nonreligious figures like snowmen and rubber ducks sometimes occupying the main roles.

What about those nativity plays that children often perform at Christmastime? They are an obvious outgrowth of the miracle plays of the Middle Ages, but the reason children (rather than adults) perform in them isn't clear. However, it's possible the tradition stems from the Victorian Era, when Christmas was recast in America and England as a child-friendly, family-centered holiday, instead of the rowdy celebration it had been in years past.

Explainer thanks Bruce Forbes of Morningside College, the author of "Christmas: A Candid History."