Songfacts®:

• "Heaven Knows" is a satirical look at the culture of the late 1980s.
  
  A brand new human being, razor sharp, all firm and tan
  All clean, all pure with a 30-second attention span
  As the clock strikes 12, and we're ready for party games
  You play blind man's bluff, and I'll play out charades
  
  The brevity of the average human attention span was old hat by the 2000s, but it was a relatively new subject in the '80s. Everything was becoming faster. Indulgence was celebrated. People were spending more time watching television and less time reading. The '80s were about flash and bling rather than substance. That is, at least, how the decade has been perceived by critics ever since it started.
  
  Even while they were happening, there was a sense that the '80s were overly commercialized and artificial in some subhuman way that no one could quite put their finger on. This was the era of the "yuppie" (young urban professional), and there seemed to be something terribly wrong about yuppies and the cocaine-and-lobster lifestyle they symbolized.
  
  A good deal of this, of course, was all perception rather than reality. Generations and eras never actually reflect the oversimplified slogan-like images they get portrayed with, but it's something that was alive even while the '80s were happening. It was the zeitgeist of the era to satirize and criticize its goofier eccentricities. Maybe that indicates that in this case, at least, the perceptions actually did come close to the reality.
• Plant unleashes a very memorable line in this song:
  
  You were pumping iron whereas I was pumping irony
  
  The 1980s were very much concerned with appearances, whether that be fashion or physique. Pumping Iron is also the title of the 1977 Mr. Olympia documentary featuring Arnold Schwarzenegger and Lou Ferrigno. The Arnold was one of the biggest movie starts of the '80s, but it's not clear if this line is a direct reference to him.
• See the whites of their eyes, then shoot
  With all the romance of the Tonton Macoute
  
  The Tonton Macoutes were a Haitian special operations unit birthed in 1959 by "Papa Doc" Duvalier. They'd been starved of funds and Papa Doc's reign was over by 1986, but the Tonton Macoutes continued to operate rather brutally for years afterwards.
  
  Saying that this group of killers had "romance" might be another statement about the shallowness and immorality of the time.
• This was the first single Plant released off of his fourth album, Now and Zen. It reached #1 on the Billboard Rock Tracks chart and #33 on the UK Singles chart.
• Surprisingly, Robert Plant doesn't have a writing credit on this song. It was composed by the songwriters Phil Johnstone and David Barratt. Both are also credited with programming on Now and Zen. Johnstone, who co-wrote eight on the songs on the album, also did keyboards and co-produced the album with Plant and Tim Palmer.
  
  According to Robert Plant: A Life by Paul Rees, Johnstone and Barratt had recorded a demo tape as part of a band named The Rest Is History. Plant's music publisher sent the tape to Plant, who particularly liked "Heaven Knows." When Plant met with Johnstone, they hit it off and decided to record Now and Zen together.
• Plant's former Led Zeppelin bandmate Jimmy Page played the guitar solo on the song. He also played on "Tall Cool One."