Thought and grief are inexorably linked in Nick's mind now, and this moving meditation heals him.
Nick then turns his focus on making camp coffee; he remembers a guy named Hopkins, who considered himself an expert on making camp coffee. We know no more about this person than is presented in this single paragraph, but the mood of the paragraph invokes a sense of "long ago," in stark contrast to the very vivid "now" that Nick is creating for himself. Then, long ago, Nick and Bill and Hopkins were young and joyous, carefree, and dreamily optimistic. Their youthful days of irresponsibility were broken, however, when Hopkins received a telegram informing him that he was suddenly very rich; back in Texas, his first big oil well had hit pay dirt. Hopkins immediately promised his two buddies that he'd take them sailing on the yacht that he was going to buy. Nick never heard from Hopkins again.
The implication is that Hopkins was swallowed by the world of money and materialism and forgot about such basic values as friendship. Similarly, Nick once believed in the glory of war and was almost killed by the machines of war, yet he survived and has come "home" to nature to restore his physical and mental health.
