Only the Phantom Knows
Forrest has joked to where the treasure is by responding “only the phantom knows." The phantom in the Marvel Comics old west series has a character who is Lincoln Slade who is also known as the Phantom Rider or the Ghost Rider.
Phantoms are also crystals that form sceptres. In Gold is the skin of Gods, Forrest said, “He’s not supposed to be carrying a scepter, but there it is. Hmmm. Sometimes it’s the aberration of an object that wets the wits of a collector." This seems to be a hint since he said to be on the lookout for aberrations and thus sceptre seems to be the obvious hint from this quote.
Phantoms are also ghosts and may be a link to ghost towns may be worth further research since they are old abandoned buildings made of wood and Forrest mentioned that his best friend Eric Slone loved to paint old dilapidated wooden buildings.
A phantom that is more aligned with Forrest Fenn is the F-4 Phantom fighter jet that was mainly employed in the latter part of the Vietnam War. Perhaps this is the phantom that knows the secret.
The most interesting interpretation of phantom is the shadow. Is it that the shadow on the cover of too far to walk knows? The shadow reminds me of Forrest special poem in The Thrill of the Chase:
ODE TO PEGGY JEAN
Today I looked up in the sky
And saw a sparrow on the fly.
What ancient secrets does he know?
Why am I here and cannot go?
Today I looked up in the sky
And saw a raven flying by.
He seemed so focused on his way
So tell me now why I must stay.
Today I looked up in the sky
And saw my shadow floating by.
It seemed so strange - I wondered why.
And now it’s gone, but where am I?
Today I looked up in the sky
And saw that I shall never die.
Forget the pain and harm you see,
My loving wife looks after me.
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