Songwriter Daniel Johnston joins Mark E. Smith, Kurt Cobain, and Anton Newcombe in the exalted club of musicians whose tales of mental illness and arrested emotional development almost cast a shadow on their discographies. That’s the unfortunate byproduct of being a chemically imbalanced but profoundly influential songwriter: Every critic and artist tends to romanticize the crippling mental illness and instability as the one true unfiltered gateway to artistic merit. Given Johnson’s pronounced bipolar disorder and touches of autism, his meticulously crafted, Beatles-inspired ruminations lead him dangerously close to savant territory. But Johnston’s work has connected with artists, regardless of their mental state, as evidenced by the 2004 release, Discovered Covered: The Late Great Daniel Johnston, in which collaborators such as Beck and M. Ward pay tribute to the meekly tragic Johnston. It might not be easy to be Daniel Johnston, but those of us who aren’t can be grateful for the fruits of his afflictions. Daniel Johnston performs with Benjy Ferree at 9 p.m. at the Black Cat, 1811 14th St. NW. $20. (202) 667-7960.