St. Alcuin of York

“Let no Catholic dare to contend against the authority of the Church; and that he may not be found to be a schismatic or a non-Catholic, let him follow the most trustworthy authority of the Roman Church;...that the members be not separated from their Head; that the hearer of the Keys of the heavenly kingdom may not reject them as having deviated from his doctrines.” (Epistle LXX [A.D. 780]).