St. Thomas Aquinas, Quodlibet II, q. 4 a. 2 co.
Respondeo. Dicendum, quod maximam auctoritatem habet Ecclesiae consuetudo, quae semper est in omnibus aemulanda: quia et ipsa doctrina Catholicorum doctorum ab Ecclesia auctoritatem habet; unde magis est standum consuetudini Ecclesiae quam vel auctoritati Augustini vel Hieronymi, vel cuiuscumque doctoris.
I answer: It must be said that the Church' tradition, which is always to be followed in all things, has the greatest authority. Since the teaching of Catholic theologians itself derives its authority from the Church, therefore, one ought to stand more with the Church's tradition than either with the authority of Augustine or Jerome or of any other theologian.