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 for that than Friday evening, when we pick up our paycheck, punch out of work and enjoy a couple days of much-needed rest and relaxation.

The euphoria of the coming weekend is summed up pretty well by the slinky groove and driving chorus of 'Sweet Emotion,' the 1975 single that helped Aerosmith break through to the Top 40 while kicking off a string of hit songs and albums that's continued, more or less unbroken, to the present day. With a percussive vocal melody that opens up into a soaring chorus, booty-shaking guitar work from Joe Perry and Brad Whitford and a distinctive bass line from Tom Hamilton, it's been one of the band's signature songs since it was released. It's also one of those cuts that sounds better the louder it gets, especially on Friday.

Fittingly, given how comfortably 'Sweet Emotion' rests on the groove, it's Hamilton's bass riff that started the whole song. As Hamilton recalled in the Aerosmith memoir 'Walk This Way,' things started coming together after producer Jack Douglas, recognizing the need for extra songs toward the end of the 'Toys in the Attic' recording sessions, asked the band members if anyone had any extra material. "I smoked a bowl or two and wrote the arrangements, the guitar parts," Hamilton remembered. "Steven [Tyler] took the intro, turned it around, changed key and we used it as the tag, the resolution of the song. Brad, Joey [Kramer], and I went home. Next time we heard 'Sweet Emotion,' it had the overdubs, the vocals, and I flipped out. I loved what they did with it."

Hamilton's enthusiasm is easy to understand. Its basic ingredients are lifted from classic blues and traditional rock, but 'Sweet Emotion' also boasts a few inventive touches that made it stand out at the time (and still sound fresh today), including a bass marimba and some nifty talkbox work from Perry. Radio responded immediately, sending the song to No. 36 on Billboard's Hot 100 chart and prompting the reissue of Aerosmith's 1973 single 'Dream On,' which gave the band its first Top 10 hit.

Ironically, the emotions behind the song's lyrics weren't so sweet. In the 'Walk This Way' bio, Tyler looked back on the tensions in the band at the time, particularly between himself, Perry and their wives and girlfriends. Admitting that a number of the lines in 'Sweet Emotion' came from his need to indulge his "angry side talking," Tyler recounted a night when Perry and his first wife refused to share some post-show drugs; the line "Can't say, baby, where I'll be in a year" served as his not-so-veiled intention to leave the group and end up "at least 1,000 miles away" from his musical partner.

As any Aerosmith fan knows, this would be far from the last time Tyler and Perry would squabble, and for a time in the '80s, it looked like their partnership had dissolved permanently. All's well that ends well, however, and after rediscovering sobriety, the band roared back to commercial prominence with 1987's 'Permanent Vacation,' starting a successful new phase in Aerosmith history. While a number of fans feel the group's more recent records lean too heavily on radio-friendly pop tracks (and material from outside writers), they're still a solid live draw, and both Perry and Tyler insist they have more music left in the tank. But even if you aren't crazy about their latter-day output, it's hard to argue with the power of 'Sweet Emotion.' So scroll on up to the top of this post, hit 'play' on the video, turn up the volume and let your weekend start now.

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