How does James Baldwin use imagery in Sonny's Blues?

Imagery:

A great block of ice got settled in my belly and kept melting there slowly all day long, while I taught my classes algebra. It was a special kind of ice. It kept melting, sending trickles of ice water all up and down my veins, but it never got less. Sometimes it hardened and seemed to expand until I felt my guts were going to come spilling out or that I was going to choke or scream. This would always be a moment when I was remembering some specific thing Sonny had once said or done.

These boys, now, were living as we’d been living then, they were growing up with a rush and their heads bumped abruptly against the low ceiling of their actual possibilities. They were filled with rage. All they really knew were two darknesses, the darkness of their lives, which was now closing in on them, and the darkness of the movies, which had blinded them to that other darkness, ad in which they now, vindictively, dreamed, at once more together than they were at any other time, and more alone.

The seven years’ difference in our ages lay between us like a chasm: I wondered if these years would ever operate between us as a bridge.