This book seeks to explore Isaiah's prophetic imagination in its fullness, attending to the historical context of his ministry while also embracing the canonical and theological unity of the text. Modern scholarship has long debated the authorship and composition of Isaiah, distinguishing between First, Second, and Third Isaiah. While these discussions have yielded valuable insights, the Catholic tradition-especially in its liturgical and canonical reading-receives Isaiah as a unified theological witness. The Church does not deny the complexity of the text's formation, but she reads Isaiah as a single book inspired by the Holy Spirit, ordered toward the revelation of Christ and the salvation of the world. This approach does not flatten historical distinctions; rather, it recognizes that the final form of Isaiah is itself a theological act, a Spirit-guided shaping of prophetic voices into a coherent proclamation.