What is the Priory of Sion?

The Priory of Sion is a very obscure group whose presence has not been established with concrete evidence. Papers relating to their existence were found in 1975 at Paris Bibliothhque Nationale, which named Da Vinci and Isaac Newton among its Grand Masters. According to the most popular theory, it is believed that the priory started out as an administrative wing of the Knights Templar. They had something (though it’s not very clear what it is) that gave them immense power and authority, even over the Pope.