Tradition vs. Sacred Tradition

It is easy to make the mistake of identifying the Sacred Tradition of the Church with the Church Fathers, as though the Fathers are the source from which the Church draws Sacred Tradition. This is inaccurate, however. The Fathers are a witness to Sacred Tradition, not a source of it. St. Thomas understands the distinction, and articulates it here:

The custom of the Church has very great authority and ought to be jealously observed in all things, since the very doctrine of Catholic Doctors derives its authority from the Church. Hence we ought to abide by the authority of the Church rather than by that of an Augustine or a Jerome or of any doctor whatever (Summa Theologica II-II, Q10, A12).

In other words: if even a Doctor of the Church contradicts the teaching of the Church, it is the Doctor who is in error.