That a spoken sound is significant is a function of its having an internal correlate in the mind. In semantic contexts, Aristotle identifies the mental state with a logos treated as a meaning or a specification of meaning in a definition. This condition on meaningful sounds is augmented by the requirement that true sentences must also correspond to extralinguistic states of affairs. A true sentence is reducible to an internalized logos, its meaning, since the sounds and/or graphic representations of it are signs of the mental state. Thus the correlation between the internal content and the external object specified by the theory of meaning becomes a threat to the existence of knowledge – or at least to our having any confidence that any particular sentence or body of assertions, such as those making up a demonstrative science, are true. Aristotle seeks to defuse this threat by in effect contextualizing the two relevant aspects of meaning, the pathema as a logos that is expressible in a natural language and the pathema as a likeness to an extralinguistic object. The context in which these are considered in the Posterior Analytics is the theory of demonstrative science, specifically, the theory of definition and the account of the origin of universals. The basic sentences or premises of a demonstrative science are true ex hypothesi. A demonstrative science is a deductive science, moreover, and this means that definitions of basic objects will be included among the primary premises.