While the wall is the most obvious and vivid demonstration of the failures of the Communist system, for all the world to see, we take no satisfaction in it, for it is, as your Mayor has said, an offense not only against history but an offense against humanity, separating families, dividing husbands and wives and brothers and sisters, and dividing a people who wish to be joined together.

1) The phrases “brothers and sisters” and “joined together” suggest a peaceful tone and highlight the need for cooperation with communists.
2) Repetition of the word “offense” develops an angry tone and emphasizes the destructiveness of communism.
3) Repetition of the word “dividing” creates a frustrated tone and suggests Kennedy is prepared to take action against communists.
4) The phrase “obvious and vivid” sets an aggravated tone and suggests Kennedy is weary of standing up to communism.