Christmas Day--25 December--was first declared a feast day by Constantine the Great in AD 325, but was not widely observed until the 19th century. Turkey was not introduced as the main part of the Christmas meal until the 16th century. Up until that time, feasting meats such as boar and game fowl were most common among the classes who could afford them. Christmas pudding, like the Christmas tree, originated in Germany. The day's meal with family and friends, as depicted on this greeting card, remains central to the season's festivities.