Kierkegaard was driven to write "The Book on Adler" after news spread that a Danish pastor, Adolph P. Adler, claimed to have experienced a revelation in which Christ dictated a new doctrine. Like many others, Kierkegaard was intrigued by Adler - but for different reasons than most. Over the eight years during which Kierkegaard worked on the manuscript, the phenomenon of Adler became a concern secondary to the larger question of authority. Kierkegaard revised the manuscript many times, and published a segment of it as "The Difference between a Genius and an Apostle" in "Two Ethical-Religious Essays", but did not publish the work as a whole before his death. The latest integral version of "The Book on Adler" is included here, along with excerpts from the earlier drafts and a sampling of writing by Adler himself.