Expositions on the Book of Psalms (Enarrationes in Psalms) by Augustine of Hippo is a vast, six-volume theological commentary, primarily derived from sermons, offering deep spiritual and doctrinal insights into the Psalms, interpreting them as Christian prayers and prophecies, and connecting them to Christ and the Church, focusing on themes like the two cities, the soul's ascent to God, and spiritual struggle. It's a foundational Patristic work, presenting a spiritual, not purely historical, reading of the text, making it a rich resource for understanding biblical interpretation and Christian life.