“If someone wants to be protected from tricks and remain healthy in the faith, he must confine his faith first to the authority of the Holy Scriptures, and secondly to the Tradition of the Church. But someone may ask, is not the canon of Scripture sufficient for everything, and why should we add thereto the authority of Tradition? This is because not everyone understands the Scriptures in the same way, but one explains them this way and another that way, so that it is possible to get there from as many thoughts as there are heads. Therefore it is necessary to be guided by the understanding of the Church …”
(St. Vincent of Lerina, Notes of a Pilgrim)