Conversation so far:
Why didn't Led Zeppelin come up with a more unique title than Led Zeppelin IV for their fourth album?
Jimmy Page decided that Led Zeppelin's fourth album would feature four hand-drawn symbols instead of a title. It is referred to as the fourth album and Led Zeppelin IV.
How did the no title but symbols idea for Led Zeppelin's fourth album go over initially?
The record company were strongly against the no title idea, but Led Zeppelin stood their ground and refused to hand over the master tapes until their decision was accepted.
How well was the album Led Zeppelin IV actually received by audiences?
Led Zeppelin IV, one of the best-selling albums in the US, was a commercial and critical success and is Led Zeppelin's best-selling, shipping over 37 million copies worldwide.
How many songs were on Led Zeppelin's fourth album?
There were eight songs on Led Zeppelin's fouth album.
Are there any other interesting aspects about the Led Zeppelin IV article?
The album cover was among the 10 chosen by the Royal Mail for a set of Classic Album Cover postage stamps issued in January 2010

Question: How did they come up with the four symbols?
Self-contained rewrite: How did the band members of Led Zeppelin come up with the four symbols for their fourth album?