A blast from the past. I don't listen much to oldies, but this song is pure funky perfection. I've been playing this song on my bass lately and while the bass line isn't hard, it's impossible to capture anything approaching the feel of the original. I've listened to several covers of the song, including some by 2 of the most highly regarded bassists of our time - Victor Wooten (Bela Fleck and the Flecktones) and Flea (Red Hot Chili Peppers), and even they can't capture the feel of the original bass line.
So kick back, twist one up if your lifestyle still allows that, and enjoy this '73 classic.