Lyric discussion by egger 

Cover art for Prodigal lyrics by Porcupine Tree

It's about considering suicide.

"This is my blood flow / this is my headstone," is talking about slitting your wrists.

"Close your eyes and let it pass," means letting your life end and being at peace with it.

It's super depressing, but an amazing song.

and what about 'If I left the stage would that be wrong?'

think you might have a point...