"Twelfth Night" is a reference to the twelfth night after Christmas Day, called the Eve of the Feast of Epiphany. It was originally a Catholic holiday and therefore, like other Christian feast days, an occasion for revelry. Servants often dressed up as their masters, men as women and so forth. This history of festive ritual and Carnivalesque reversal, based on the ancient Roman festival of Saturnalia at the same time of year (characterized by drunken revelry and inversion of the social order; masters became slaves for a day, and vice versa), is the cultural origin of the play's gender confusion-driven plot.