Songwriting isn't a science. It is certainly an art, and with that comes an unpredictable process. It can take years for a song to be completed. That was the case for Don Henley's "Heart of the Matter." Learn why Henley had to work on this song for years before releasing it, below.

[RELATED: Don Henley and Stevie Nicks' 2015 Duet, a Ballad Originally Released by Garth Brooks' '90s Alter-Ego Chris Gaines]

I got the call today

And I didn't wanna hear

But I knew that it would come

An old true friend of ours

Was talkin' on the phone

She said you found someone

Henley felt moved by this song and its themes. So moved, in fact, that he worked on "Heart of the Matter" for years before it was finished. Henley, believing we all need forgiveness from someone, hoped this song would have a universal appeal. In the decades since this song's release, Henley's hope has proved true.

Henley's "Heart of the Matter" is one of his most lyrically robust. It's not hard to imagine it took him quite some time to pen this hit. Henley collaborated with J.D. Souther and Mike Campbell. It was Campbell that helped Henley finally flesh this song out. Something about Campbell's advice in the studio helped him to get over a mental block about writing about forgiveness. According to the co-writer, he got the impression that Henley was particularly proud of the lyrics he landed on.

"I know he was especially proud of that one," Campbell once said. "He told me that lyric was something he had been trying to write for a long time and it finally came out the way he liked it, something he really wanted to sing. A lot of people like that song."

[RELATED: The Don Henley Lyric Inspired by a Burger Joint]

Saying that "a lot of people like" this song is an understatement. "Heart of the Matter" worked its way up the Billboard charts upon its release and helped to prop up Henley in his solo career. Revisit this hit, below.