Lots of people don't know who it is because it's pre- Stevie Nicks/Lindsay Buckingham, but it's actually IIRC their 5th or 6th album.
I must have heard it about 1976-7 (I was 8-9 years old, but the song is from 73) and clearly remember the funky shuffle groove and how odd they lyrics were. It really does have a hypnotic effect. I believe it's their first song to be in prolonged rotation on the radio (I heard it on AM!)
I actually didn't realize until a few years ago that the singer is Bob Welch (-Ebony Eyes, which to me always sounded like Steve Miller).