This is the final paragraph of the speech JFK intended to deliver at the Dallas Trade Mart on November 22, 1963, the day he was assassinated :
“We in this country, in this generation, are – by destiny rather than choice – the watchmen on the walls of world freedom. We ask, therefore, that we may be worthy of our power and responsibility, that we may exercise our strength with wisdom and restraint, and that we may achieve in our time and for all time the ancient vision of “peace on earth, good will toward men.” That must always be our goal, and the righteousness of our cause must always underlie our strength. For as was written long ago, “except the Lord keep the city, the watchman waketh but in vain.”
Now this words are in a monument in Dallas. 50 years after his death, a lot has changed. US citizens still mourning him and in its majority not believing he was killed by an alone assassin as the official investigation concluded.