The quote from "My Heart Is Bursting" most contributes to the assertive tone of Satanta’s speech is All the chiefs of the Kiowas, Comanches, and Arapahos are here to-day; they have come to listen to good words. I hope the answer helps.
In the speech "My Heart Is Bursting" Santana wanted to transmit to the people the importance of maintain the lifestyle of the Kiowa tribe, he said “I love to roam over the prairies. There I feel free and happy, but when we settle down, we grow pale and die.” They want them to remain in their land in the speech he uses assertive tone like this quote “I have heard that you intend to settle us on a reservation near the mountains. I don't want to settle.” The passionate tone he adopted gave strength to the ability of Santana of using emotions to persuade.
