John,
For me, it's the Commencement address JFK gave at American University on June 10, 1963, part of which is excerpted below:
http://www.ratical.org/co-globalize/JFK061063.html
Today, should total war ever break out again -- no matter how -- our two countries would become the primary targets. It is an ironic but accurate fact that the two strongest powers are the two in the most danger of devastation. All we have built, all we have worked for, would be destroyed in the first twenty-four hours. And even in the cold war, which brings burdens and dangers to so many countries, including this nation's closest allies -- our two countries bear the heaviest burdens. For we are both devoting to weapons massive sums of money that could be better devoted to combating ignorance, poverty and disease. We are both caught up in a vicious and dangerous cycle in which suspicion on one side breeds suspicion on the other, and new weapons beget counterweapons.
In short, both the United States and its allies, and the Soviet Union and its allies, have a mutually deep interest in a just and genuine peace and in halting the arms race. Agreements to this end are in the interests of the Soviet Union as well as ours -- and even the most hostile nations can be relied upon to accept and keep those treaty obligations, and only those treaty obligations, which are in their own interest.
So, let us not be blind to our differences -- but let us also direct attention to our common interests and to the means by which those differences can be resolved. And if we cannot end now our differences, at least we can help make the world safe for diversity. For, in the final analysis, our most basic common link is that we all inhabit this small planet. We all breathe the same air. We all cherish our children's future. And we are all mortal.
He was advocating an accomodation with the Soviet Union, and there were definitely people in 1963 who looked on that as tatamount to treason.
Steve Thomas