I’m not sure if the Commonwealth Letters can be found in a book. But looking around eBooks from JM that I had downloaded a couple of years ago from the CFD site, I ran across the Tactics & Strategies Manual which is a collection of a whole bunch of blog articles that JM wrote a few years before he left us. The short articles are very similar to the Commonwealth Letters. The manual is huge, like almost 300 pages and is very well put together. He was such a great writer and a genius.
William, if you go to resources section, see the drop down menu. to find the Commonwealth Letters.
Keep in mind that these were written many years ago, from 1978 to 2009, but the history seems to repeat itself and the information on how to deal with problems remains the same. Jack Miller was brilliant and always had a good Plan B or exit strategy.