The Letters were retrieved from storage by Bernard DeVoto, an editor who had been hired by Twain's survivors, probably looking to earn a little from his unpublished work. DeVoto put them in order and added them to other essays of an irreligious nature: The Diary of Adam, The Diary of Eve, and others. Twain's daughter, Clara Clemens, then the executor, put the kibosh on the project. Some have speculated that she worried that Twain would roast in hell if they were published (that is, if he wasn't already there for having just conceived of them).
Yes, that was only the first time I read the Letters. I've read them many times since. Even though I have bought countless copies of them, and given away many, I now have a copy permanently stored on my Kindle. I'll be able to survive even the most tiresome queue at the DMV without complaint. However, there is a danger in reading this collection in a public place. Someone may send for the men with butterfly nets from the laughing academy to retrieve me from the floor where I end up every time laughing hysterically.