Answer:
Juan Thomas means when he says "the structure" is that the poor people are cheated from birth, but they made it through it. He is scared for Kino. It is important to the story because it foreshadows the things that happen to Kino.
He set a giant boulder at the mouth of the cave.
Emerson said that "To be great is to be misunderstood." He also said that a great person constantly changes. He cited examples of great men like Pythagoras, Socrates, Jesus Christ, Luther, Copernicus, Galileo, and Newton. A great individual must also not violate one's nature even though that person may not be understood by the society.
Hope it helped!
