Classic rock is about heavy hooks, power chords, and tight harmonies, but it’s also about letting loose and enjoying the good times — and there’s no better time than Friday evening, when we pick up our paycheck, punch out of work, and enjoy a couple days of much-needed rest and relaxation.

Today, we're paying tribute to a song that captures the feeling of a lazy weekend more successfully than most: The Doobie Brothers' 'Black Water.' A cut from the band's 1974 album 'What Were Once Vices Are Now Habits,' 'Black Water' went on to become their first chart-topping hit when it reached No. 1 on the Billboard Hot 100 in March 1975 -- but it took an unusual series of series of events to make it happen.

The album's first single, 'Another Park, Another Sunday,' eked into the Top 40, but according to the Tim Morse book 'Classic Rock Stories: The Stories Behind the Greatest Songs of All Time,' Doobies guitarist Tom Johnston believes its chart life was shortened thanks to a lyric about how "radio brings me down" -- something station program directors didn't take kindly to. When subsequent single 'Eyes of Silver' failed to gain traction, the label took the odd approach of sending a three-year-old track, 'Nobody,' to radio; fortunately, while all these shenanigans were going on, DJs were busy discovering the 'Another Park' B-side -- which was, as you've no doubt figured out by now, 'Black Water.'

Boasting a laid back vibe and a decidedly more bluegrass-influenced sound than early hits like 'Long Train Runnin'' and 'China Grove,' 'Black Water' tells the story of time spent floating down the Mississippi River on a homemade raft, all set to a beautifully laconic melody supported by a delicate acoustic guitar and Appalachian strings. While most listeners probably hadn't spent time watching catfish jumping under a Mississippi moon, just about everyone can understand lines like "I ain't got no worries / 'Cause I ain't in no hurry at all." That isn't just a classic rock couplet, it's a manifesto worth aspiring to.

And then, of course, there's that 'Black Water' breakdown. One of the most recognizable a cappella arrangements in rock and roll, it was suggested by producer Ted Templeman, a former member of Harper's Bizarre who remembered the trick from his old group's cover of the Simon & Garfunkel song 'The 59th Street Bridge Song (Feelin' Groovy).' As he later recalled, "[producer Lenny Waronker] did the same thing for 'Feelin' Groovy' where he pulled the track out...so I stole the idea from my old producer."

It's remained one of the Doobie Brothers' signature songs for nearly 40 years, and while a substantial portion of its appeal rests on those supremely mellow lyrics, it was also helped by the fact that it didn't sound like anything else on the radio at the time -- and really, it still doesn't. "It started off as an acoustic song, just an acoustic guitar for the first third of the record, then the drums come in," offered Templeman when asked to analyze its success. "Records weren't like that on the radio. There were formula pop records then. There's little things that speed up and slow down because we didn't stay right with the rhythm machine, but it's a pretty good record."

A pretty good record indeed, and seeing as how we've helpfully embedded a vintage live version of the song right here, you can just click 'play' below, turn up the volume, and let the weekend start...now.

Watch the Doobie Brothers Perform 'Black Water'