This paper aims to demonstrate from the perspective of rhetoric that what is called “dream-telling communities,” although seen as peculiar occurrences particularly identified in the medieval period in Japan, are a universal activity of human beings that makes society work. The dream-telling community is a sort of society formed by those who are aware of their being aboard the same boat and, by sharing their dream narrations, nurture their sense of unity, with the intensified aspiration for their shared ambition. The act of dream-telling, making the individual experience of dreaming dreams shareable with community members, turns it into being social. This paper argues that the act of dream-telling, which is indispensable for the formation of dream-telling communities, plays a role of epideictic discourse. Typically identified as ceremonial oratories, the epideictic, one of the three types of rhetoric identified by Aristotle, concerns praise and/or blame. Ch. Perelman and L. Olbrechts-Tyteca (1971) foregrounded the hitherto underestimated importance of the epideictic; “it strengthens the disposition toward action by increasing adherence to the values it lauds” (70).