How does repitition create meaning in this excerpt

Which passage from kennedy's inaugural address is an example of an allusion? to our sister republics south of our border, we offer a special pledge-to convert our good words into good deeds-ir new alliance for progress but this peaceful revolution of hope cannot become the prey of hostile powers a call to bear the burden of a long twilight struggle, year in and year out, rejpicing in hope patent in tribulation it a free society cannot the many who are poor, it cannot save the few who are rich