Frank Buchman is relatively unknown to the public these days but had a tremendous impact on the world in the 20th century. He led a group which became known as the Oxford Group (and later Moral Re-Armament [MRA]) which provided a number of the principles that birthed Alcoholics Anonymous and its variations.
He seems to have been a man of endless energy, acute psychological insight, and great vision. Lean's book provides an in-depth biography of Buchman. It is fairly exhaustive but not entirely satisfying.
At times it reads like an apology (in the sense of a defense) of Buchman and MRA. The number of quotations and individuals referenced crowds out the narrative at times and it becomes hard to see the forest for all the trees.
I would have liked to see the attention to detail but in additional endnotes or footnotes rather than in the body of the text.
In addition many of Frank's foibles are left until later in the book and I feel this may not be ideal as it gives the picture of an almost super-human when Buchman certainly had his challenges.
The thing that most fascinates me about Buchman was his ability to work with individuals of widely divergent views. He was a friend of capitalists, socialists, and communists and managed to bring them together. Buchman was a Christian but worked with individuals from many different faiths including Islam, Buddhism, and Hinduism.
It seems to me that there is much to be learned from Buchman's life and work - both in how to do things and how not to.