5 The Holy Fathers well knew all this by practical experience, and they never cease to extol the sacred Scripture and its fruits. In innumerable passages of their writings we find them applying to it such phrases as "an inexhaustible treasury of heavenly doctrine,"(16) or "an overflowing fountain of salvation,"(17) or putting it before us as fertile pastures and beautiful gardens in which the flock of the Lord is marvellously refreshed and delighted.(18) Let us listen to the words of St. Jerome, in his Epistle to Nepotian: "Often read the divine Scriptures; yea, let holy reading be always in thy hand; study that which thou thyself must preach. . . Let the speech of the priest be ever seasoned with Scriptural reading."(19) St. Gregory the Great, than whom no one has more admirably described the pastoral office, writes in the same sense: "Those," he says, "who are zealous in the work of preaching must never cease the study of the written word of God."(20) St. Augustine, however, warns us that "vainly does the preacher utter the Word of God exteriorly unless he listens to it interiorly;"(21) and St. Gregory instructs sacred orators "first to find in Holy Scripture the knowledge of themselves, and then to carry it to others, lest in reproving others they forget themselves."(22) Admonitions such as these had, indeed, been uttered long before by the Apostolic voice which had learnt its lesson from Christ Himself, Who "began to do and teach." It was not to Timothy alone, but to the whole order of the clergy, that the command was addressed: "Take heed to thyself and to doctrine; be earnest in them. For in doing this thou shah both save thyself and them that hear thee."(23) For the saving and for the perfection of ourselves and of others there is at hand the very best of help in the Holy Scriptures, as the Book of Psalms, among others, so constantly insists; but those only will find it who bring to this divine reading not only docility and attention, but also piety and an innocent life. For the Sacred Scripture is not like other books. Dictated by the Holy Ghost, it contains things of the deepest importance, which in many instances are most difficult and obscure. To understand and explain such things there is always required the "coming"(24) of the same Holy Spirit; that is to say, His light and His grace; and these, as the Royal Psalmist so frequently insists, are to be sought by humble prayer and guarded by holiness of life.
Source: Providentissimus Deus (Vatican.va)