The Proto-Gospel of James, a kind of "Gospel Before the Gospels," was one of the most influential non-canonical writings throughout the Middle Ages. The narrative does not focus on the life of Jesus but on the supernatural birth, young life, betrothal, and pregnancy of his mother Mary.

From this Gospel come many traditions that remain important in the Catholic and Orthodox traditions (Joseph was an old many; Mary was a perpetual virgin; Jesus' "brothers" were sons of Joseph from a previous marriage); and the accounts it presents -- the miraculous birth of Mary, her upbringing in the temple, the details of her giving birth, and, well, a postpartum inspection to make sure she was a virgin -- are fascinating to readers of any religious or non-religious persuasion.

But what's it really all about? In this special episode, Bart interviews an expert on the Proto-Gospel, Christopher Frilingos, Professor at Michigan State University, in order to find out.