I'm extensively involved in peace/antiwar work. I hope that people will be able to discern that Andrew Cohen is talking about internal peace vs. social peace and justice. [it delights me to see that others here see peace & social justice as inextricable things, that they necessarily complement one another]
I'd re-phrase Cohen: "As long as we are seeking peace for our Self above all else, we will never know what it means to live at the very edge of the possible." For me, conscientiously working for peace is to live at the very edge of the possible, and again for me, that is world peace.