What makes Ponyboy think of the Robert Frost poem?

While Ponyboy and Johnny are hiding out at the church on Jay Mountain, Ponyboy wakes up one morning and goes outside to smoke a cigarette. As he is smoking, Ponyboy looks at the beautiful dawn as the sun slowly comes up over the horizon. Pony notices that the sky is lighter in the east and that there is a thin strip of gold across the horizon. As Ponyboy is taking in the stunning scene, Johnny comes outside and comments on how pretty the sky looks. Ponyboy then mentions that he wishes he could paint a picture of the sky while it is still fresh in his mind. Johnny then says, "Too bad it couldn't stay like that all the time" (Hinton 66). Johnny's comment reminds Ponyboy of the Robert Frost poem, "Nothing Gold Can Stay." Ponyboy recites the poem for Johnny but fails to explain the meaning behind the poem. Later on in the novel, Johnny ends up understanding the meaning of the poem and realizes that Robert Frost was describing the transience of nature and life. On his death bed, Johnny tells Ponyboy to "Stay gold" (Hinton 126).