Why did Plato think a complete statement needs both a name and a verb?

In his dialogue Sophist, Plato argued that a complete statement (logos) must consist of at least one name and at least one verb because these two elements are fundamentally heterogeneous and serve distinct functions in communication.12

Plato defined a name as the sign of an agent of an action and a verb as the sign of an action itself. He observed that simply placing two names or two verbs in succession—such as "lion stag" or "walks runs"—fails to create a meaningful proposition. A statement requires the combination of these two different types of words to express a thought that can be evaluated as true or false. This insight marked a significant development in the analysis of language, as it moved beyond viewing words in isolation to investigating the internal structure of statements.213