Bl. Pius IX's favorite manual of "We, therefore, congratulate you, Beloved Son, on the manner in which you have treated of the elements of this science. Setting aside the false systems of more recent writers, you have followed the Angelic Doctor and those who, guided by the light of the Church, the Mistress of truth, have, by their wisdom and diligent labor, wonderfully illustrated philosophy. From their works you have drawn the doctrines by which to form the minds of the young men confided to your care."