It's only taken me about 5 1/2 years, but I finally found out how to back up this blog. An on-line friend, Michael Bauman, had the URL for one of his blogs nabbed (somehow) by cybersquatters and was looking for a way to get his content back. The fact that this could happen to him spooked me to a salutary degree, and I did some googling and found that it is possible to back up a Blogger blog such as this one fairly easily using some space on one's own hard drive and the "export" function. Settings ---> Other ---> Export blog. The content is saved in .xml format for easy import into a new blog. Fortunately, despite the cyber-bandits, Dr. Bauman was able to grab his content in this way and move it over to his other, untouched blog, "The Right Word."
I'm sure anyone who reads this has known for a long time how to back up a Blogger blog. (Wordpress has a similarly easy function, I hear, though it doesn't grab uploaded images.) Just in case you haven't done this for a free personal blog: Take my word for it; it's extremely easy, takes about a minute, can be repeated as needed, and will provide extra security against various mishaps.