How does the narrator describe Jack's lessons with Yegudkin?

Yegudkin sits in the chair next to Jack as Jack plays his horn. Yegudkin sings along with Jack's playing, gesticulating wildly as he hits the high notes Jack plays. When Jack takes a rest, Yegudkin talks to him about the United States and Russia. Yegudkin believes the United States is mistaken in their belief that Russians are a backward people not to be feared.