In a close reading of Plato's use of substituting terms for metaphor and of the notion paradigm in his later dialogues, as well as of Aristotle's criticism of the overall 'paradigmatic discourse' in Plato, the paper tries to elaborate some new arguments, not included or insufficiently recognised in recent scholarly writing, for the position that Plato's conception cannot be reduced to the old-fashioned metaphysical model of the universal-particular relationship. He offers, instead, a dynamic model of dialectical cross-relations of genera, species and particulars that acts productively in several theoretical directions, aiming both at coherence and foundation of discourse. The paper supplements a related study on the use of paradigm in modern and contemporary philosophies of science, trying out a Wittgensteinian solution to some enigmas in Plato's notion of the 'ultimate paradigm' at the 'metaphysical' level of his theory of 'highest principles'. It is part of a broader research for a book on metaphors in the discourse of philosophy and sciences.