According to many accounts, those 6 words constituted the entire speech. A little digging will tell you that’s not quite so, but it IS those 6 words that stood out. That summed up the essence of what needed to be heard in that environment, at that point in history. It was the right message, at the right time.
The Comfort Zone is a funny place. We hear all the time that people want to be in their Comfort Zones. That athletes excel when they are in their Comfort Zone. That world-class performance occurs inside Comfort Zones.