The song is played in C
Tune the guitar 1/2 step down, as all the avantasia's songs.

Intro (figure it out): C.... (a long tim in C, C4, C9...) then Am, Em, F, G....

C
Coming from the wastelands
        G              C
Full of reason, common sense
            Am              Em
Where their principles are blocking minds
    F                G
And you don't understand

C
Giving you belive,
          G                 C
You never touch, you never see
           Am              Em
But if you dare to try to grip it
         F              G
You're accused for heresy

[Gabriel:]
This part is usualy played by another guitar 1 step dow, this way
(if you're playing alone, this part is 1/2 step down (Eb)

E                B
Here I stand to find the truth
E               B
And for ought I know

(1st. guitar again)

C          G       Am
You're the one to show me
Em      F              G       C
You can tell my spirit how to grow

e|-------------3----------
B|------3-3/5-----3H5------
G|----3-------------------
D|--3---------------------
A|------------------------
E|------------------------

C
No, the more I try
             G           C
The more confusion on my mind
        Am          Em
And no matter how I try
           F                  G
I feel my eyes seem to stay blind

[Tree of Knowledge:]

C             G         C             G
No use in analysing, forget about alchemy
             Am            Em
Because the secret of all truth
        F                      G
Is the quest for - and you'll feel

(second guitar again)

      E              B
Oh! When you knock right on the door
      E                B
"Forever locked" they say

(1st guitar)

   C     G        Am      Em
A little man will let you in,
     F               G          C     G
For you have always tried - to get inside

Eb                   Bb               Gm 
You're in quest for more to find the core
              Cm                   Gm
Your journey still ain't over
      Cm            Gm      G# Bb
Your quest is your purpose, go on
Eb                   Bb               Gm 
You're in quest for more to find the core
              Cm                   Gm
It will be - never- over
      Cm            Gm      G# Bb
Your quest is your purpose, go on

Eb                   Bb               Gm 
You're in quest for more to find the core
              Cm                   Gm
Your journey still ain't over
      Cm            Gm      G# Bb
Your quest is your purpose, go on
Eb                   Bb               Gm 
You're in quest for more to find the core
              Cm                   Gm
It will be - never- over
      Cm            Gm      G# Bb
Your quest is your purpose, go on...

Eb                   Bb               Gm 
You're in quest for more to find the core
      Cm            Gm      G# Bb
Your quest is your purpose, go on...
Eb                   Bb               Gm 
You're in quest for more to find the core
              Cm                   Gm
It will be - never- over
      Cm            Gm      G#   Bb     Eb
Your quest is your purpose, go...o ... on