John Darnielle, the singer-songwriter at the core of The Mountain Goats, may be the most prolific songwriter in the world. Since he started recording in lo-fi on a tape machine by himself more than 30 years ago, he’s released about 600 original songs.

I’m not ashamed to say that, while I’ve listened to his catalog several times, I still struggle to identify his songs. I have a freakishly good memory, but there’s too many even for me to remember them all. The upside of the size of his catalog is that, while there some songs repeated on the second of his two recent nights at The Birchmere, the two sets were quite different from each other, and from what he played at Wolf Trap in August.