Roman writers understood Saturnalia as a yearly return to the lost Golden Age, the reign of Saturn when, in the myth, there was no slavery, no property, and no toil, so that the festival's inversions, slaves feasting as equals, masters serving, hierarchy suspended, briefly re-enacted a paradise of primal equality. Its midwinter timing, its exchange of gifts, its candlelight, and its licence have long invited comparison with later December celebrations, above all Christmas, and it is sometimes claimed that Christian festivity simply took over the Roman feast.
Historians urge caution here. Saturnalia, the Kalends of January, and the birthday of Sol Invictus all clustered in late December, and Christmas grew up amid that cluster, but a shared season and a shared taste for gifts and lights do not prove direct borrowing of any one custom from any one feast. The atmosphere of Roman midwinter surely coloured what came after; the details of descent are far harder to trace than popular accounts suggest.