How does Hunter S. Thompson use imagery in Fear and Loathing in Las Vegas?

Imagery:

"Old elephants limp off to the hills to die; old Americans go out to the highway and drive themselves to death with huge cars." (Part I, Chapter 3, p.18).

"I took another big hit off the amyl and by the time I got to the bar my heart was full of joy. I felt like a monster reincarnation of Horatio Alger: A Man on the Move, and just sick enough to be totally confident." (Part II, Chapter 14, p.204).