A brief history of Christmas and Advent

I thought this article was really interesting. For example, I didn't realize that Christmas wasn't widely celebrated in the early church:

Church Fathers such as Augustine didn't include a commemoration of Christ's birth in their lists of holidays at all. Early Christians focused their attention on Easter, the holiest day in the Church's calendar, the solemnity of solemnities....The earliest surviving record of a specific celebration of the Nativity is a sermon by St. Optatus, bishop of Mileve in Africa, from about 383.

The whole thing is worth reading.