We never know how high we are

We never know how high we are (1176)

Emily Dickinson 

 

We never know how high we are  
  Till we are called to rise;  
And then, if we are true to plan,  
  Our statures touch the skies—  
   
The Heroism we recite
  Would be a daily thing,  
Did not ourselves the Cubits warp  
  For fear to be a King—

Found at American Academy of Poets here.