In the medieval period officials in the Catholic Church claimed that the Pope held supreme authority over all spiritual and secular matters by virtue of this passage from the sixteenth chapter of the book of Matthew:

13. When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, "Whom do men say that I the Son of Man am?"

14. And they said, "Some say that thou art John the Baptist; some Elias; and others, Jeremias, or one of the prophets."

15. He saith unto them, "But whom say ye that I am?"

16. And Simon Peter answered and said, "Thou art the Christ, the Son of the living God."

17. And Jesus answered and said unto him, "Blessed art thou, Simon Barjona; for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.

18. And I say also unto thee...