This chapter, and the quest for the Crystal Key, is an homage to the Rush album 2112, particularly the song "The Temples of Syrinx", which is exactly where the key is hidden. This song also includes the lyric "and the meek shall inherit the earth."
Right now, Parzival is just hoping to inherit the Crystal Key. Inside the temple, behind a waterfall, he finds a 1974 Gibson Les Paul guitar crammed into a rock, sword-in-the-stone style.
Parzival easily extracts it, and can't resist the urge to play the Rush song "Discovery," about a hero who finds a guitar behind a waterfall.
When he plays the song, a secret message appears, letting him know that the Third Gate cannot be unlocked alone.
He places the guitar on an altar, where it transforms into the Crystal Key.
No hint this time, just a single letter "A" monogrammed on the handle.
That "A" is the same symbol that adorns the front gates of Castle Anorak—Halliday's castle.
The Sixers have already figured this out, of course, and have surrounded the castle with an invincible shield using the Orb of Osuvox operated by a ninety-ninth level wizard. As long as the wizard is touching it, the shield cannot be broken. (We want to know why doesn't the wizard just stand inside the shield?)
Wade has a plan, "a bold, outrageous plan that would require epic amounts of luck to pull off" (27.55). Here goes nothing.