Sheepdog motif by Lieutenant Colonel Dave Grossman.
Dwight D. Eisenhower Farewell Address to the Nations 
If you have no capacity for violence then you are a healthy productive citizen: a sheep. If you have a capacity for violence and no empathy for your fellow citizens, then you have defined an aggressive sociopath--a wolf. But what if you have a capacity for violence, and a deep love for your fellow citizens? Then you are a sheepdog, a warrior, someone who is walking the hero’s path. Someone who can walk into the heart of darkness, into the universal human phobia, and walk out unscathed." --Dave Grossman