Christmas, is an annual holiday celebrated on December 25 or January 7 that commemorates the birth of Jesus of Nazareth but is also celebrated by many non-Christians as a secular, cultural festival. For many centuries, Christian writers accepted that Christmas was the actual date on which Jesus was born. However, in the early eighteenth century, some scholars began proposing alternative explanations. Isaac Newton argued that the date of Christmas was selected to correspond with the winter solstice, which in ancient times was marked on December 25.