What is the purpose of the italicized paragraph beginning with "And why did I..." (Chapter 13) In Invisible Man

The italics denote the importance of the narrator's thoughts, and what is, in fact, a discovery about himself. The vision of the evicted couple get through to the narrator in a way that almost nothing else has. In their presence he finds his own relation to the past; they parallel his own sense of estrangement, and they in a sense bring him home.