The Clouds Lyrics
There’s been a complication
It seems your heart needed a break
From pumping the blood through your veins,
and keeping the oxygen okay.
I still see your face in the day.
And I see your eyes in the bottle that was way too tall
I finished it just to see if we could talk.
Now I’m speaking with your ghost again
It’s telling me that I don’t listen.
Can we be friends,
In another lifetime
I might pretend that we are right now.
I summoned demons from a dying tree
I took a long walk off a short levee
I drank the poison from a black moon seed,
and then I saw you.
I felt your kiss in a dream I had
I felt your skin in a monument
Then I went home to live a brand new life without you
I buried all our things
Beneath the giant shadows of the clouds.
And they will stay there underground,
but no matter what I do I never will stop talking to you.
I never did get the last word in,
And you said I always did.

This will be a short summary interpretation:
I believe that again, like many Republic of Wolves song's, that it is up to any interpretation. The songs meaning may change to you based on how you feel. It's a part of the good music.
However, I think this song is a direct prequel to the song "Wood/Bricks" if it were story line of a relationship. This song is explaining what could be the time where there is bickering and ignoring each other in a dying relationship.

Wow this song is really powerful.

I summoned demons from a dying tree I took a long walk off a short levee I drank the poison from a black moon sea
You can hear it much clearer on the demo Gregg posted on his blog.

Lnksyr is right [I summonded demons from a dying tree]
its very clear

I'm pretty sure it's about a loved one dying and him wishing she was still around. I know the feeling, my mom died after a long battle with cancer last September. You always wonder if they are still out their somewhere but you have no real way of knowing.