Henri Nouwen was a great promoter of the practice of spiritual direction, but he never wrote a book on the subject. This is surprising since he wrote a wide array of books on just about any given subject in the Christian spiritual quest. He did write a number of articles on the subject, and there are a number of unpublished article and writings pertaining to the subject. Two close friends and associates of Nouwen, Michael Christensen and Rebecca Laird have compiled these writings into a book that is entirely Nouwen's writings (without commentary) and could just be the book Nouwen would have written if he had approached the subject.
While the book is meant to be an introduction to spiritual direction for a person interested in the subject, Nouwen's rich writing and his ability to speak to the heart will make this book a treasure for any reader. The book covers the basic topics that any book on spiritual direction should include. It begins with life's basic questions, looking at direction in life, the quest for God, and prayer. While the book is ecumenical in approach, Nouwen is indebted his roots in the Roman Catholic tradition. He does not mention different spiritual traditions specifically, e.g. Jesuit, Trappist, or Carmelite, but readers familiar with these approaches will see glimpses of each as well as Nouwen's unique ability to include the longing and goodness of humanity in general as a way of approaching God.
For most of Christian history, spiritual direction was practiced almost exclusively by clergy and religious, and more often than not, the spiritual director was the person's confessor. It was not the domain of most members of the laity and from what I understand, it was all but non-existent in Christian traditions outside of the Roman Catholic and Orthodox traditions. Nouwen was one of the early proponents of making this practice available to anyone who desires it. The book will not only be enriching for readers but will be an important resource in years to come.