Some classic rock bands define the bands that wrote them. The Eagles' "Take It Easy" is one of the band's most essential songs, but it was co-written by a rock star who was never part of the band. The song was almost left in the dustbin of history.

Jackson Browne was a rock star who had a string of hits in the 1970s and 1980s, including "Running on Empty," "Somebody's Baby," "You're a Friend of Mine," "Tender Is the Night," and "Boulevard." Before all that, he started writing a little ditty called "Take It Easy." He had an issue with fixing the song.

During a 2003 interview with The Uncool, The Eagles' Don Henley discussed "Take It Easy." "We gave Glenn [Frey] a nickname, The Lone Arranger," the "Boys of Summer" singer recalled. "He had a vision about how our voices could blend and how to arrange the vocals and, in many cases, the tracks. He also had a knack for remembering and choosing good songs. Jackson had shelved 'Take It Easy' because he couldn't complete it, but it was Glenn who remembered the song from some time earlier and asked Jackson about it one day."

Frey discussed the song with Browne. "I told him that I really liked it," he said. "'What was that, man? What a cool tune that is.' He started playing it for me and said, 'Yeah, but I don't know -- I'm stuck.' So he played the second unfinished verse and I said, 'It's a girl, my lord, in a flatbed Ford, slowin' down to take a look at me.' That was my contribution to 'Take It Easy,' really, just finishing the second verse. Jackson was so thrilled. He said, 'OK! We co-wrote this.'"

While Browne co-wrote "Take It Easy," it remains one of The Eagles' defining songs. While a lot of classic rock is about the good times, The Eagles' music is full of anxiety. The band was so uptight that their song "Take It Easy" still manages to be tense. In addition, the tune exemplified the slick country rock sound that The Eagles would build upon for the rest of their career.

"Take It Easy" was a rare thing -- a minor hit that changed everything. The tune peaked at No. 12 on the Billboard Hot 100 and stayed on the chart for 11 weeks. While "Take It Easy" missed the top 10, it started a string of hits for The Eagles that lasted for the rest of the 1970s and had a huge influence on other bands.

"Take It Easy" appeared on the album Eagles. That record climbed to No. 22 on the Billboard 200 and spent 49 weeks on the chart. The record produced two other hit singles: "Witchy Woman" and "Peaceful Easy Feeling." The former reached No. 9 and spent 13 weeks on the Billboard Hot 100. Meanwhile, the latter peaked at No. 22 and spent 12 weeks on the Billboard Hot 100.

"Take It Easy" is a great song -- and it wouldn't be the same without Browne's genius.