Saturnalia: The Reason We Celebrate Christmas in December

Saturnalia was the Roman holiday marking the winter solstice. It was named after the Roman god Saturn, in his aspect of the god of seed and planting. It was originally celebrated on December 17th, but by the late of the late Republic it was celebrated from December 17th to December 23rd. The Emperor Augustus tried to limit the time of celebration to three days, but it was expanded to five under the Emperor Caligula.

In the Roman calendar, the Saturnalia was designated a holy day, or holiday, on which religious rites were performed. The Temple of Saturn, the oldest temple in Rome, had been dedicated on the Saturnalia, and the woolen bonds which fettered the feet of the ivory cult statue within were loosened on that day to symbolize the liberation of the god.

It also was a festival day. After sacrifice at the temple, there was a public banquet, which Livy says was introduced in 217 BC. Afterwards, the celebrants shouted "Io, Saturnalia!" at a riotous feast in the temple.

The Saturnalia was the most popular holiday of the Roman year. Catullus describes it as "the best of days," and Seneca complains that the "whole mob has let itself go in pleasures." Pliny the Younger writes that he retired to his room while the rest of the household celebrated. Cicero fled to the countryside. It was an occasion for celebration, visits to friends, and the presentation of gifts, particularly wax candles, perhaps to signify the returning light after the solstice. Homes were decorated with greenery. Candles and lamps chased away the spirits of darkness. 

Aulus Gellius relates in his Attic Nights that he and his Roman compatriots would gather at the baths in Athens, where they were studying, and pose difficult questions to one another on the ancient poets, a crown of laurel being dedicated to Saturn if no-one could answer them.