Until the 16th century, the donation of Constantine was called upon and brandished relentlessly as the foundation for the universal destiny of St. Peter's successors. It was supposed to justify the Catholic Church's temporal power as well as its seat in the city of Rome. The humanist Lorenzo Valla exposed the forgery in 1440, but it was not made public until 1506. This very first instance of diplomatics was one of the founding acts of modern textual criticism.