“But it is a very mournful thing, by which the ravings of human reason go to ruin when someone is eager for revolution and, against the advice of the Apostle, strives ‘to be more wise than it behooveth to be wise’ [cf. Rom. 12:3 ], and trusting too much in himself, affirms that truth must be sought outside of the Catholic Church in which truth itself is found far from even the slightest defilement of error, and which therefore, is called and is ‘the pillar and ground of the truth’ [1 Tim. 3 15 ].”  Pope Gregory XVI, Singulari nos affecerant gaudio, 1834