I got home (late, but I won't go into that) and went to put on the water for the rice. "Why isn't the water coming out hot?" I wondered. Oh crud. The pilot is out on the water heater. Mmmm. The label is so degraded with age that I can't read it, but I think I'm supposed to hold down this red button while holding fire on the pilot. Why isn't it lighting?
The last time I had a plumbing emergency (months ago) after I finally got my plumber to come fix it, I told him I had a bunch of stuff I wanted done on a non-emergency basis, including replacing the water heater, and I've been waiting for him to call back when he has time to deal with it. I sure hope it doesn't take two weeks to get him to come out this time.
Update: Aha, if I turn the main knob just past the "pilot" position, the notch in that knob lines up with the button, allowing said button to descend farther when pressed. And then the pilot lit. And now the main burner is working on getting the water back up to temperature.
I still need to get the plumber to get in here and replace the water heater. But hopefully it won't be a matter of cold showers until I can get through to him.