If there was ever a book that made my reading of ancient sources puny and small, this is Without explicitly stating it, Lubac is offering his support for a four-fold model of Scriptural interpretation: history, allegory, tropology (morality), and anagogy (spiritual). Most important to Lubac is the legitimacy of a possible allegorical reading of scripture.
The basis of Lubac's argument is strikingly simple: the early Church through the medieval period always practiced it. Most of the book is a historical recitation of the problems of untying the historical problems of what entailed a four-fold reading of scripture, where divergences and convergences occurred, origins of allegorical readings, and opposition to allegorical readings. The problem as I see it is that Lubac is unconvincing if you were already unconvinced. Both Lubac's support for allegory and the implied opposition to allegory are, to my mind, a priori.
That being said, Lubac's work is satisfying on three fonts: 1) for those convinced of the benefits of allegory--it provides a historical basis for such practice, 2) for those opposed--it provides a background for understanding your perceived opponent. And "perceived" is significant. Nowhere does Lubac discount the historical. In fact, he argues that the historical provide the foundation for the allegorical. This emerges out directly out of Lubac's sacramental ontology of the materialist world, and 3) for those seeking an intellectually honest alternative to the historical-critical methodology of the 20th century. Lubac offers a possible reading of Scripture that is historically honest and grounded but seeks read Scripture in a broader context that is made alive through the resurrection of Jesus Christ and the work of the Holy Spirit.
Lubac overwhelms us with a prodigal recitation of ancient and medieval sources. Lubac was clearly operating on another plane. His reading of those ancient sources is given with an overwhelming confidence that the reader knows exactly what he is talking about all the time. Frustratingly for me, I did not.
Despite overwhelming me at times, this book is a gem. It should be required reading for anyone who has grown tired of the historical-critical method of Biblical scholarship that has dominated the 20th century.