I am sorry but its not plagerized music
[sic]
I don't want to turn this into a "pee-ing" contest and I love Led Zeppelin (did you watch the youtube videos?). A large number of their songs are lifted note for note (lead parts) and word for word (lyrics) from music that comes from as far back as the 20's. If that's not plagiarism, I don't know what is. Also, credit was never given on the early album releases to anyone other than the Jones, Bonham, Page and Plant. If you watch the video, it's claimed there were out of court settlements and recognition in the credits on later releases of the same albums.
The rock and roll industry is rife with "borrowing" sounds, riffs, lyrics, etc. (ask George H about "My Sweet Lord/She's So Fine"), but directly lifting is more rare (but prevalent in Zep's work). Heck, artists like John Lennon would invite powerful young upstart musicians to play at his home (with recorders running) to "develop" new ideas. The young guys were just happy to be there and share the "stuff" to impress industry greats. This is for a guy that already had a ton of creative juices flowing (Lennon).
On the other hand, Zeppelin did an incredible job of arranging their music and developed a "sound" that was matched by none at the time. Bonham was possibly the most "original" of the group. Plant had (and to a degree still has) an incredible "signature" voice. But.... it cannot be argued that their music and lyrics were original. Most of it was lifted.