Back to the stunned Sophie and her two instructors.
The Grail hasn't exactly been a secret. Teabing shows her a bunch of books that talk about how Mary was really the Holy Grail.
Because she posed such a threat to the Church, Mary Magdalene gained a bunch of pseudonyms, including the Rose.
(The rose's symbolism gets discussed at length. These two men can be exhausting with their love of academia.)
Anyway, Mary was pregnant when Christ was crucified, so she was forced to flee to France (then known as Gaul) for her and her child's safety.
She found refuge with the Jews there, and gave birth to a daughter, Sarah.
Because she and her daughter were royalty to the Jews, they chronicled their lives prodigiously, and their subsequent family tree is amongst the documents contained in the Holy Grail archives.
Those Holy Grail documents are suspected to also include pre-Constantine documents about Christ's works, and a "Q" document, that might have even been written by Jesus himself, and a diary written by Mary Magdalene.
If you're confused, then so is Sophie. If Mary is the Holy Grail, why are the documents referred to with the same name?
Oh. Because Mary's buried in a tomb with the documents. They're now one and the same. Ah ha.
There's more. The Priory not only defends the secret of the location of the Holy Grail, but also the bloodline of Christ itself.
In the fifth century, one of His direct descendants married into French royal blood, creating a lineage known as the Merovingian bloodline.
The Merovingian family's pretty well-known in France, because they founded Paris.
One of those descendants, Godefroi de Bouillon, is the guy who founded the Priory, and ordered the Knights Templar to recover the Sangreal documents.
So. Teabing sums it up like this: The Priory have three jobs:
1: Protect the Sangreal documents.
2: Protect the tomb of Mary Magdalene.
3: Nurture and protect the bloodline of Christ.
Sophie gets the chills. Her grandfather needed to tell her the truth about her family. He called her "Princess Sophie". Could she be one of the Merovingian survivors?
Rémy rudely interrupts via intercom, requiring Teabing to meet him without Langdon and Sophie.