To know when one’s self is interested, is the first condition of interesting other people.

Pater’s aphorism links personal attentiveness to communicative power. The ability to recognize what genuinely engages one’s own mind—rather than what one thinks ought to be engaging—becomes a prerequisite for engaging others. Implicit is a theory of influence grounded in authenticity and self-knowledge: interest is contagious when it is real, because it shapes tone, selection of detail, and the energy of expression. The remark also suggests a discipline of introspection for writers, teachers, and conversationalists: before trying to persuade or entertain, identify the precise point of one’s own curiosity or stake in the matter. Without that inner “interest,” attempts to interest others risk becoming mechanical or performative.