What does "Fortune fame mirror vain" mean in Metallica's The Memory Remains?
The first two lines probably go together in a sentence as “Fortune, fame mirror vain” and can translate to “both fortune and fame mirror what is vain.” So this basically says that fame and fortune reflect false pride, or baseless pride. That one who has those things and waves them around do so to express how proud they are, but to no avail (another definition of the word “vain”). And then it goes to the next line, “gone insane”, to express how one goes insane from their false pride of fame and fortune, or simply grows too attached to the fame and can’t stand to lose it. However, they can’t get over this anxiety of losing fame because “[…] the memory remains”.
BTW the correct lyrics are (note the comma in the first line):
But the memory remains
As shown in this lyric booklet that accompanies a Japanese release: