After the service, Moses shifts the mood and spins into a breakdance before picking up a guitar to play. The inmates clap and cheer. The video, posted four months ago, has 40,000 views.

But back in the 1950s, ’60s and ’70s, a San Antonian by the name of Martha Mood elevated the bar on such work to what can confidently be called high art. In her style, technique and subject matter, ...