Complete happiness can look so much like complete terror that it's hard to tell them apart.
You can never see a plant grow, but they do.
You can almost believe what you know is not true when you really have to.
Life is all we have, and if we can't look at it honestly, are we really living?
If people knew who the angels were, they would be very nice when they saw one and would still do their same evil garbage when they thought none were around. Knowing who they are defeats the purpose.
People will do and think whatever it is they have to in order to survive.