"Trampled Under Foot" was included on the 1975 album Physical Graffiti. By the time "Trampled Under Foot" came out, criticisms about Led Zeppelin lifting ideas from African American artists were commonplace, regardless of whether or not these claims had any substance. In Melody Maker Chris Welch reported that Robert Plant "admitted" that Robert Johnson's "Terraplane Blues" had been the source of inspiration for this song.
[1] The Terraplane was a car manufactured from 1932 to 1938 by the Hudson Motor Car Company. Recording in 1936, Robert Johnson used this car as a sexual metaphor in "Terraplane Blues". "Trampled Under Foot" employs a similar device, though not mentioning any model of car specifically. Every conceivable thing to do with cars is used as a sexual image in "Trampled Under Foot". ("trouble-free transmission helps your oil's flow," just to take an example) Other than that general idea, the lyrics of "Trampled Under Foot" are completely distinct from "Terraplane Blues", as the two songs do not share even a single line. In fact, the themes of these songs differ"Terraplane Blues" is about infidelity while "Trampled Under Foot" is about giving in to sexual temptation.
According to Robert Godwin, when Led Zeppelin played at Earl's Court, John Bonham accused Robert Plant of stealing the lyrics for "Trampled Under Foot" from "Terraplane Blues". Godwin writes, "In fact he didn't steal the words, but Johnson's guitar arrnagement is curiously similar to the keyboard arrangement of 'Trampled Underfoot'".
[2] A more common reference is the one Chris Welch makes in his book Dazed and Confused, where he mentions the influence of Stevie Wonder's "Superstition" on "Trampled Under Foot" (although a review in Rolling Stone suggested the track owed more to Kool and the Gang).
[3] On "Superstition," from the 1972 album Talking Book, Stevie Wonder played a Hohner Clavinet
[4] and John Paul Jones used the same instrument on "Trampled Under Foot".
[5] While both riffs are funky with a similar pattern, they are readily distinguishable. Any comparisons that have been made between "Trampled Under Foot" and other songs are just reference points"Trampled Under Foot" is Led Zeppelin's alone. While the car as sexual metaphor may have been borrowed from Robert Johnson and the funky electric piano riff inspired by Stevie Wonder, as with all of their best tracks, Led Zeppelin synthesized their influences and produced something original.
Recommended Listening
 
Robert Johnson - The Complete Recordings
 
Stevie Wonder - Talking Book
Compilations of Original Versions
None of the compilations focuses on the origins of "Trampled Under Foot".
Chris Welch, Led Zeppelin, Dazed and Confused: The Stories Behind Every Song (NY: Thunder's Mouth Press, 1998), p. 89. Jim Miller, Rolling Stone, March 27, 1975, reprinted at Super Seventies RockSite!.
Brian Kehew, "The Keyboards of Led Zeppelin and John Paul Jones", http://www.geocities.com/jpjkeys/clavinet.html. Kehew points out that Jones used a later model of the Hohner ClavinetStevie Wonder had used a Model C, while Jones used the Model D.
 
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