He is perhaps the best speaker in America of this generation, but his speech before the huge crowd in the U.N. Plaza on that afternoon in mid-April was bad; his words were flat, the drama and that special cadence, rooted in his Georgia past and handed down generation by generation in his family, were missing. It was as if he were reading someone else’s speech. There was no extemporizing; and he is at his best extemporaneously, and at his worst when he reads. There were no verbal mistakes, no surprise passions. When he finished his speech, and was embraced…