[ETL]

"Be polite. Be professional. But, Have a plan to kill everyone you meet. Be courteous to everyone and friendly to no one."

That philosophy no doubt works well on the battlefield, or on the streets of many inner cities.

[norton]

"Be polite. Be professional. But, Have a plan to kill everyone you meet." And...
"Be courteous to everyone and friendly to no one."

"That philosophy no doubt works well on the battlefield, or on the streets of many inner cities...

Being aware of your surroundings, cognizant of their dangers (and opportunities), and having options if you need to respond to them isn't limited to combat or back alleys.