They never talk about themselves but listen to you while you talk about yourself, and keep up an appearance of being interested in the conversation.

The line satirizes a familiar social type: the person who seems charmingly attentive but whose “interest” is largely performative. By stressing that they “never talk about themselves,” Jerome implies that the listener’s restraint is not necessarily humility or empathy; it can be a tactic that flatters the speaker and smooths social interaction. The humor lies in the uncomfortable recognition that many conversations are sustained by vanity—people enjoy talking about themselves—and that skilled social operators can exploit this by offering attentive silence. The quote thus critiques conversational egoism and the theatrical nature of politeness.