The Wisdom of Each Other: A Conversation Between Spiritual Friends (1998) by Eugene Peterson is a unique, though beneficial, book. It is unique because it contains a series of letters addressed to Gunnar Thorkildsson, whom Peterson described as "not an actual person with an existence documented by birth certificate and social security number", though Peterson insists that the details were grounded in actual encounters he had over the years.
In each of the several dozen letters Peterson penned, he responded to some actual circumstance of Gunnar's life--return to the faith, the poor quality of too much Christian literature, church politics, and the tranquility of canoeing. The unifying theme, as far as I am concerned, is a spirituality that does not exist above everyday life but rather enters into it and moves around in it. Peterson wisely showed us that. Although not my favorite book by Peterson, it is a welcome addition to my collection.