Many of our customs of Christmas stem from the Roman Saturnalia, a winter festival spanning several days beginning on 17 December. Saturn (equivalent of the Greek Cronus) was a major Roman god of the seasons, the calendar, agriculture and the harvest, depicted holding a sickle in his left hand and a bundle of wheat in his right. In Roman mythology after Jupiter defeated him, Saturn fled to Rome and established a Golden Age there as an earthly king, a time of perfect peace and harmony. When the era was over, Saturn departed to lie asleep on a magical island, but will one day return and bring back another golden age. The Feast of Saturnalia was meant to recapture something of this perfect time – no taxes could be collected, no wars declared and no prisoners executed. Presents were given and feasts and merrymaking were the order of the day.
It was an annual period of license, when the customary restraints of law and morality were thrown aside and everyone gave themselves up to excessive mirth and jollity.  Catullus called it ‘the best of days’. Masters changed places with their servants, and the slave might dine with his master or even be waiting on by him. Every house had its Saturnalicius Princeps (Master of the Saturnalia), the Lord of Misrule, chosen by lot, who had to act as foolishly as possible and was free to order others to do his bidding. His command was law, whether it was to dance naked, to sing, suffer a dunking in icy water, or carry a flute girl round the house. Trees were decorated and houses hung with holly and other greenery. Slaves wore the badge of freedom known as the pillius and were exempt from punishment; there was a school holiday and a special market. Senators left aside their togas for more informal clothes, and people greeted each other with “Io Saturnalia” (‘Hail/praise Saturn’) rather in the manner we say “Merry Christmas”.
 James Frazer, The Golden Bough, Macmillan Press, London, 1976