It has been seven years since I last wrote a blog shamelessly promoting my book Practical Home Theater: A Guide to Video and Audio Systems. In fact, I’ve never told the whole story of why I wrote the book, why I update it every year, and why it’s lasted so long&#8212the latest edition, dated 2018, is the 17th. Addicted as I am to numbers divisible by five, I might have waited for the 20th edition. But this blog is long overdue. Think of it as a delayed reaction to the 15th.