Louis Bouyer was a Frenchman who lived from 1913-2004. He was a Lutheran minister who converted to Catholicism and became a priest. He is of interest because of his involvement in the Second Vatican Council and his close relationship with various popes on liturgical and theological commissions. These Memoirs have been published in French for quite some time and only recently have been translated into English.
Most people are interested in these memoirs for his personal insights into the popes, which are always positive, and his unique insights into the commissions he worked on, which are sometimes contrary to the normal positive narrative told by others of the period. He is the one who who told the alternative history of Eucharistic Prayer II, famously quipping that he would never pray Eucharistic Prayer II "because I wrote it." His wry view of the Council, at the height of his frustration, is worth quoting, both as an example of his opinion and of his wit:
In the best case scenario, that of a truly ecumenical council in the traditional meaning of the term, i.e. actually representative of an undivided Christendom, the most that divine assistance can ensure for the Apostles' successors is the absence of any possible error in the doctrinal definitions such assemblies venture to produce. But, short of this extreme case, any dosage of approximation, insufficiency, or simple superficiality are to be expected from even so sacrosanct an assembly.As insightful as it is, his involvement in the Council is really only one chapter of the book. The rest of it is the story of a man born on eve of World War I, who became a Lutheran minister and couldn't resist the draw of the Catholic Church, and who ended up advising Cardinals and Popes. He's traveled the world speaking and teaching, and yet he never comes across as a worldly man. He's simply an academic, a man who studied and prayed hard, and who had the gifts necessary to be a part of big events. These memoirs are written in an entertaining, intelligent style, and I would highly recommend them.