Cajetan’s analogy theory is usually evaluated in terms of its fidelity to the teachings of Aquinas. But what if Cajetan was trying to answer questions Aquinas himself did not raise, and so could not help to answer? Cajetan’s De Nominum Analogia can be interpreted as intending to solve a particular semantic problem: to characterize the unity of the analogical concept, so as to defend the possibility of a non-univocal term’s mediating syllogistic reasoning. Aquinas offers various semantic characterizations of analogy, saying it involves, for instance: signification per prius et posterius; or a ratio propria which is only found in one analogate; or diverse modi significandi with a common res significata. Examined in turn, it is clear that none of Aquinas’s rules for analogy solve the semantic problem described. Cajetan thus cannot be reasonably expected to have intended his analogy treatise primarily as an interpretation or systematization of Aquinas’s teaching on analogy.