Aeterni Patris §22

²² The ecumenical councils, also, where blossoms the flower of all earthly wisdom, have always been careful to hold Thomas Aquinas in singular honor. In the Councils of Lyons, Vienna, Florence, and the Vatican one might almost say that Thomas took part and presided over the deliberations and decrees of the Fathers, contending against the errors of the Greeks, of heretics and rationalists, with invincible force and with the happiest results. But the chief and special glory of Thomas, one which he has shared with none of the Catholic Doctors, is that the Fathers of Trent made it part of the order of conclave to lay upon the altar, together with sacred Scripture and the decrees of the supreme Pontiffs, the Summa of Thomas Aquinas, whence to seek counsel, reason, and inspiration.