At some point last night, my Address Book on my Mac kind of lost all its entries. Very strange, but I suspect it might be my fault. While I could probably have figured out how to recover it, it might have taken me an hour or two to search for ways to do it and to figure out something that would work. And that’s not even guaranteed.
But you know what? This is a job for Time Machine. It took about thirty seconds, and all my contacts are back. Yay!