How can a President influence a country long after he leaves office?

this concerns the complex question of memories, legacy and lasting images.Take Kennedy and Nixon,for example, one seen as full of youthful promise, a fresh approach, a dynamic,charismatic leader-Nixon,by contrast , as the scheming,manipulative,machiavellian,opportunistic chancer whose ambitions defeated any shreds of integrity he might have once possessed.But are these stereotypes?If they leave a legacy of powerful images annd memories,are these realistic,rooted in reality, or prime examples of the triumph of style over substance? You decide.