How we cite our quotes: (Paragraph)
Quote #4
"What we got now is Brokeback Mountain. Everthing built on that. It's all we got, boy, f***in all, so I hope you know that if you don't never know the rest." (117)
Brokeback has a way of reaching out from the past and shaking the pair up: it reminds them of what they had and (more importantly) the fact that they can never have it again, which is the central tragedy of the story.
Quote #5
What Jack remembered and craved in a way he could neither help nor understand was the time that distant summer on Brokeback when Ennis had come up behind him and pulled him close, the silent embrace satisfying some shared and sexless hunger. (120)
Here's the link between Brokeback and the pair's emotional state, and the way they associate the one with the other. It's a powerful memory. It's also very Romantic in the big "R" sense, as Jack filters memories of his love through the physical location of Brokeback.
Quote #6
"He had some half-baked idea the two a you was goin a move up here, build a log cabin and help me run this ranch and bring it up." (142)
Jack's Dad is using a memory of something Jack said to twist the knife into Ennis. Memory is a very painful thing in this story, whether Ennis is remembering something himself or having some insensitive jerk do the remembering for him.