I dont know

Have  I  said  I  understand?

 Forgive me, I'm shortsighted.  

In my  firsts  in life, 

 I've  been told;  

You  think  you  know  what this  is? 

 You  think  you  know  what that  is? 

 You have no idea at all. 

 I  thought  I  know  the  difference; 

 between the  danger  and the  dark,  

between the  devil  and  the  demon,

 between serenity  and  silence. But I have no idea.  

Have  I  said  I  know?  

Forgive me, I don't know.