There’s something perverse about watching a man in pain sing some of the most beautiful songs ever written, which is how I spent two nights in November of 2010, chasing Merle Haggard’s bus down Interstate 10 out of Louisiana, into Texas, off toward oblivion.

A few months earlier, Haggard had been named a Kennedy Center honoree, and I had been sent to a casino parking lot in Lake Charles to interview the country legend about his life and times. Stepping aboard his tour bus, I immediately realized I was speaking with a wounded man.

Haggard was 73. A cancerous chunk of his lung had been removed in 2008 and he was just now recovering from a related infection that burned deep in his chest. When I told him that it seemed insane for a man in his state to be out on the road, he nodded in solemn agreement. He said that touring was a compulsion, an obligation, a trap he didn’t feel that he deserved to get sprung from.

Haggard — who died Wednesday on his 79th birthday — sang about things like that all of the time, telling stories of human turbulence with supreme elegance. En route to becoming one of the greatest songwriters in history, he was first a hero of the Bakersfield sound — a bright, sleek, rock-tinted dialect of country music that initially spread across the California oil fields near where the singer grew up.

Haggard filled his most indelible songs with heavy regrets, the kind that haunt life’s most tragic transactions. The sting of loneliness burns through the effects of alcohol in “The Bottle Let Me Down.” A loving mother fails to save her no-good son in “Mama Tried.” A prisoner prepares for his execution in “Sing Me Back Home.” Gorgeous American songs about ugly American situations, all of them.

And somehow, after our heavy chat on the bus, Haggard sang them inside that smoky Louisiana casino, and without too much trouble. Sure, his voice sounded like it had been working hard for at least five decades, but it didn’t sound pained. The crowd’s applause was polite and reverent. Haggard smiled a few times.

The next night of the tour? It couldn’t have been more different. He was booked at a honky-tonk outside of Houston — a rowdier room illuminated by the glow of 20th-century neon and the flash of 21st-century flat-screens, each locked on ESPN.

Buzzed and chatty, the young crowd was either oblivious or ambivalent to Haggard’s pain as he slowly moved toward the center of the stage and began to sing. The feeling seemed mutual. Song after song, Haggard seemed unable to tap into the crowd’s vitality.

There wasn’t anything romantic about it. He was just another singer playing another honky-tonk, making some drunks dance and shout. There wasn’t any glory in the room. Just wonderful songs. Maybe that’s how Haggard wanted it to be.