ChapterIII-VII. Readings from the Fathers and Church Writers
159. In keeping with the tradition of the Roman Church the office of readings has, after the biblical reading, a reading from the Fathers or church writers, with a responsory, unless there is to be a reading relating to a saint (see nos. 228-239).
160. Texts for this reading are given from the writings of the Fathers and doctors of the Church and from other ecclesiastical writers of the Eastern and Western Church. Pride of place is given to the Fathers because of their distinctive authority in the Church.
161. In addition to the readings that The Liturgy of the Hours assigns to each day, the optional lectionary supplies a larger collection, in order that the treasures of the Church's tradition may be more widely available to those who pray the liturgy of the hours. Everyone is free to take the second reading either from The Liturgy of the Hours or from the optional lectionary.
162. Further the conferences of bishops may prepare additional texts adapted to the traditions and culture of their own region,  for inclusion in the optional lectionary
as a supplement. These texts are to be taken from the works of Catholic writers, outstanding for their teaching and holiness of life.
163. The purpose of the second reading is principally to provide for meditation on the word of God as received by the Church in its tradition. The Church has always been convinced of the need to teach the word of God authentically to believers, so that "the line of interpretation regarding the prophets and apostles may be guided by an ecclesial and catholic understanding." 
164. By constant use of the writings handed down by the universal tradition of the Church, those who read them are led to a deeper reflection on sacred Scripture and to a relish and love for it. The writings of the Fathers are an outstanding witness to the contemplation of the word of God over the centuries by the Bride of the incarnate Word: the Church, "possessing the counsel and spirit of its Bridegroom and God,"  is always seeking to attain a more profound understanding of the sacred Scriptures.
165. The reading of the Fathers leads Christians to an understanding also of the liturgical seasons and feasts. In addition, it gives them access to the priceless spiritual treasures that form the unique patrimony of the Church and provide a firm foundation for the spiritual life and a rich source for increasing devotion. Preachers of God's word also have at hand each day superb examples of sacred preaching.