In the title of this paper, the three names of well-known philosophers stand in for three different theories of predication, and the corresponding semantic theories of the Indo-European copula, which I will identify as the verbalist (or Geach’s  Fregean) theory, the nominalist (or two-name theory), and the adverbialist (or inherence) theory, respectively. After a brief characterization of each and remarking on the relative insignificance of the syntactical issue of whether the copula is syntactically marked in a language or not, I will raise the issue of which of these theories is correct. After concluding that this is a pseudo-problem, because given their logical equivalence they should yield equivalent truth-conditions for the sentences they generate, I will raise the pragmatic issue of which of these theories yields a conceptual framework that is most suitable for dealing with metaphysics. After clarifying the criteria of this sort of suitability, I will argue that the framework that best satisfies these criteria is the adverbialist or inherence theory, as represented here by the thought of Aquinas