I was traveling last week when I heard the news that Glenn Frey, frontman for the legendary 70s band The Eagles, passed away.  Like many classic rock fans, I’ve enjoyed many of the Eagles songs throughout my life and own their two greatest hits albums.

But I didn’t really get a full appreciation for the band until I used the occasion of Frey’s passing to watch the epic 2013 documentary on the band, The History of the Eagles.

The documentary really gets at the heart of why the band was so good for so long, and it boils down to two things: harmonies and songs.  On the harmony front, The Eagles mastered beautiful multi-part vocals that gave all their tunes a distinctive, quasi-country feel.

And the documentary shows how this sound almost didn’t happen.  During one of their early recording sessions with legendary British rock producer Glyn Johns, everyone was getting frustrated.  Johns, who’d worked with Led Zeppelin and The Rolling Stones, was about to give up on them.

But then he heard them harmonize on one of their obscure tunes, and he was sold.  He built that sound into all their early work.  Later in their career, The Eagles even became masters of the lead guitar harmony, most famously on the outro guitar solo to “Hotel California.”

The second big factor was what Jack Nicholson described simply as “repertoire,” as he was standing next to Jackson Browne at an Eagles reunion show in the 1990s.  The band was awesome at churning out catchy hits throughout the 1970s, led by Frey and Don Henley on drums (mostly).

The documentary can be depressing, as it’s largely a story of how creative masterminds Frey and Henley ditched their surrounding bandmembers over decades.  The musicians who stayed had to be totally subservient.

Still, you have to give credit where credit is due: Henley and Frey were talented songwriters who were not afraid to collaborate in search of a hit.  They even let newbies write songs, if they were any good.  This kind of pragmatic approach to finding a good song and presenting it well served the band fabulously.

I recommend the documentary, and watch the whole thing so you can catch the somewhat bizarre postscript with Governor Jerry Brown (he dated Linda Ronstadt in the 1970s, and The Eagles started out as her backing band).  And then maybe you’ll be able to get this scene from the Big Lebowski out of your mind: