That’s the line that starts Robert Johnson’s “Preaching Blues,” but forget about haunting reverb and creepy contemplation—the blues goes walking at such a brisk pace you have to hustle to keep up. The horror of the piece turns out to be that something (heard through the guitar) is chopping at us constantly and inescapably as though we’re going around in the wheels of a hurtful machine. (This is “Preaching Blues,” so it could be the word of the Lord chopping on us, all for our own good, amen.)
“Preaching Blues” is so brisk, in fact, that you might not want to let it represent the blues; you might set it apart as a proto-rocker like “Sweet Home Chicago” or “I Believe I’ll Dust My Broom.” But I hear serious bluesness in how the hard-driven guitar, Johnson’s slide knocking loudly on its neck, catches the chunky scrape of the human body’s real progress in the world. The clincher for my interpretation is a passage where a few little mischievous irregularities in the guitar part (right after “tore me all upside down”) sound like things getting caught in the machine, not stopping the rhythm but suggesting enough cloggage to remind us how our own bodies are roughly handled in this process. There’s difficulty just in being alive, don’t you know; indeed there’s a friction in materiality itself.
Difficult embodiment is a great blues theme that often shows up in rock, but often doesn’t. It’s not there when the music machinery sounds very well oiled. But it’s there in that great line of virtuosic almost-stumbling irregular rocking that runs through “Black Dog” and “Barracuda” and the many gut-tugging moments in Metallica, a line in which “Preaching Blues” should hold a place of honor.
At song’s end, Johnson sees a way to break free before we’re all chopped up:
Goin’ to the ‘stillery
Stay out there all day
Bit of a dilemma, I’d say.
 I develop this claim, keeping a focus on Robert Johnson, in “Blues and Our Mind-Body Problem,” Popular Music, 11 (January 1992), 41-52.