After opening up a sufficiently large hole to pull the wires out, I noticed they were ... gross. This box had been sealed up before the advent of wire nuts and modern electrical tape, plus all the connections were made with soldered pig tails. It was pretty much disgusting. After clearing off all the gook, we tested the circuit. Success! Apparently the "mystery" light switch wasn't such a mystery after all.
Flash forward about a week (to yesterday). Knowing the circuit was a go, we tested to make sure the light actually worked. Again, success. And a funny picture.
What remains? To actually hang this sucker. In order to put a secure hook into the ceiling, I wanted to make sure I was screwing into one of our rafters. Since the junction box wasn't actually screwed into a rafter, I went into the attic and measured the distance from the box to the rafter. Next, I estimated where the rafter should be based on my measurement. Then I used a stud finder to find the position of the rafter in two positions near my position. Finally, I drew a line between my measurements (linear regression ftw), and I screwed that sucker in. Success! Of course, being the engineer I am, I had to go back up into the attic to get a confirmation before I hung anything from it. (Hanging a chandelier on a hook that falls out of the ceiling goes under the category of "Man, that was stupid.")
Anyway, I'll cut to the chase. We're pretty happy with it. Voilà!
You may have been wondering, "What's Lindsay doing anyway?" She probably would have been watching TV, but it turns out that this light is on the same breaker as our TV. So no dice. Instead, she was planting vegetables in her cool little inside planter deal. Check it out!