To understand how the world works, you need to open your eyes to the clues around you.  How do we know who is spreading darkness versus the light if we take everything at face value?  

To be pure of heart is not the same as being naive, but quite the opposite.   The pure of heart know the world can be a cruel and unfair place, but dispite this, want to at least have their life represent a point of light, a little star that never gives up the desire to shine it’s light – even if the universe’s darkness tries to oppress it.