Commonsense beliefs about the mind are routinely operative in human discourse, where they serve as prolific resources from which to generate discourse/understanding while often remaining in what Pierre Bourdieu calls “the realm of the undiscussed.” As a study of how mind-related beliefs serve as a resource for rhetorical invention, this essay (1) provides insight into an important and pervasive category of doxastic beliefs and (2) brings into focus the powerful undertow of doxa’s routine discursive work. It does so, in part, by analyzing Dr. Benjamin Spock’s best-selling child-rearing manual, The Common Sense Book of Baby and Child Care, together with reactions it elicited from readers. These show how mind-related beliefs can generate discourse while being suppressed in the discursive iteration, resulting in fragments, enthymemes, implications, and presences/absences. Moreover, published in multiple editions over many years, Spock’s book demonstrates the inventional implications of historical changes in widely shared beliefs about the mind.