I think it's about blaming someone else for something you've done.
'A song about someone else' - blaming someone else.
'Looking too closely' - as you would have to admit guilt.
'No no no no' - but you can't admit to it.
Admitting guilt is painful and you would 'hurt yourself'.
However you're accountable for what you've done as the 'truth is like blood underneath your fingernails'.
And really when you're looking for someone else to blame it's just 'you in the mirror'.
I think it's about blaming someone else for something you've done. 'A song about someone else' - blaming someone else. 'Looking too closely' - as you would have to admit guilt. 'No no no no' - but you can't admit to it. Admitting guilt is painful and you would 'hurt yourself'. However you're accountable for what you've done as the 'truth is like blood underneath your fingernails'. And really when you're looking for someone else to blame it's just 'you in the mirror'.
Beautiful song and lyrics.