In his forward to R. C. Sproul’s Knowing Scripture, J. I. Packer observes that Protestant theologians are in conflict about biblical interpretation. To illustrate the diversity of biblical interpretations, William Yarchin pictures a shelf full of religious books saying different things, but all claiming to be faithful interpretations of the Bible. Bernard Ramm observed that such diverse interpretations underlie the doctrinal variations in Christendom. A mid-19th century book on biblical interpretation observed that even those who believe the Bible to be the word of God hold the most discordant views about fundamental doctrines. The Catholic Church asserts the capital importance of biblical interpretation and Catholic scholars recognize some diversity in the Bible. This allows for an openness of interpretation as long as it stays within the Catholic Church’s theological tradition. So it is that theological factors set the parameters for interpreting the Bible that Catholics believe to be the word of God. According to Roy B. Zuck, such parameters disallow the widely differing interpretations that make it possible for Protestants to prove almost anything by the Bible. For Catholics, the Catholic Church is the official custodian and interpreter of the Bible. Therefore, Catholicism's teaching concerning the Sacred Scriptures and their genuine sense must be the supreme guide of the commentator. The Catholic commentator is bound to adhere to the interpretation of texts which the Church has defined either expressly or implicitly. Furthermore, the Church Fathers are of supreme authority whenever they all interpret in one and the same manner any text of the Bible, as pertaining to the doctrine of faith or morals; for their unanimity clearly evinces that such interpretation has come down from the Apostles as a matter of Catholic faith. Pope Benedict XVI indicated in Verbum Domini that "Christianity […] perceives in the words the Word himself, the Logos who displays his mystery through this complexity and the reality of human history." He encourages a "faith-filled interpretation of Sacred Scripture" that has been "practiced from antiquity within the Church’s Tradition […] recognizes the historical value of the biblical tradition." It "seeks to discover the living meaning of the Sacred Scriptures for the lives of believers today while not ignoring the human mediation of the inspired text and its literary genres". Layers of meaning Christian biblical hermeneutics considers the original medium as well as what language says, supposes, doesn't say, and implies. David L. Barr states there are