Demons run when a good man goes to war
Night will fall the drown the sun
When a good man goes to war
Friendship dies and true love lies
Night will fall and dark will rise
When a good man goes to war
Demons run, but count the cost
The battle's won, but the child is lost
(Steven Moffat)
This is from Dr. Who, but it could be from so many epic stories and apply to so many lofty ideals. Not the least of which is the Dr. Who franchise.