violence and its seeds

I've been thinking about war, use of force, and any form of coercion or manipulation I might exert on another.

I wonder, is it ever reasonable, useful, or long-term profitable to influence another person?

I wonder, is it ever justifiable to retaliate?

I wonder, is it possible to just let things go (where does the anger go? where do we put it?) and move on?

Where do we move on to?

There is a higher view here somewhere, I just can't see it yet.