What: Indigo Girls with the Chattanooga Symphony & Opera.
When: 8 p.m. Saturday.
Where: Tivoli Theatre, 709 Broad St.
There's something mysterious about songwriting, said Amy Ray.
Ray, one half of the longtime folk rock duo Indigo Girls, is coming to Chattanooga on Saturday. She and her partner, Emily Saliers, will perform alongside the Chattanooga Symphony & Opera, the first symphonic concert the band has played.
Through more than 30 years of playing together, Ray and Saliers always had an understanding that songwriting is a personal process, at least for them.
The two actually write and arrange separately and then bring their music to each other.
"We don't ask each other to explain the songs, because we just have an understanding that it's kind of a mystery, songwriting is."
For example, she said, she doesn't know the emotional significance Saliers attaches to the song "Ghost," which Ray praises as "one of the most well-crafted songs she's ever done. It's so great to perform it because it's so full, lyrically and melodically."
While trusting each other came fairly naturally, trusting others was a greater challenge, she said. "That's a point you get to, but we definitely need input from other people in order to be challenged."
Such trust, she said, is necessary when taking on a challenge like the upcoming CSO concert.
"When you play with such a large entity, you have to really be correct and yet have honesty and emotion at the same time, not overthink it or try to play so correctly you lose the meaning of the song. ... You have to just let go," she said. "It's not going to work unless you do. You just have to believe."
The Indigo Girls are known for simple melodies and poetic lyrics, which, Ray said, reflect life.
Part of the title track of their latest album, "Beauty Queen Sister," was inspired by S.E. Hinton's coming-of-age novel "The Outsiders."
"It's kind of a conglomerate of things -- a friend I was paying tribute to, and "The Outsiders," and the idea of young love, and the struggle of life and family, the loss of innocence in a twisted way."
While many of their songs have a sense of political consciousness, Ray said that is not an intentional attempt to send a message, it's simply "a lens we see things through."
"Both of us have always had a tendency toward activism, even when we were young, separate from our music."
A lot of the songs on "Beauty Queen Sister," she said, reflect and honor the band they played with in Nashville. It is often the bands or musicians they play alongside who inspire them and influence their music.
"We've been influenced by so many people." Her inspirations, she said, range from Patti Smith and James Taylor to The Clash. Currently, they're being backed by a band called The Shadowboxers.
She gets demos from friends, or friends of friends, and said she wonders "how can there be so much great music out there, but there is."