In this article I claim that Leibniz's 1670 preface to a sixteenth-century text on rhetoric by Marius Nizolius offers a historical perspective on the relationship between figurative language and performativity in philosophical discourse. To begin with, although Leibniz argues in the Preface to Nizolius against the use of rhetoric, eloquence, and specifically tropes in philosophical discourse, nevertheless his prescriptions for philosophical clarity implicate a "channel of tropes" in what could be described as a retroactive, performative assignation of proper usage. Moreover, the example that Leibniz supplies to illustrate the channel of tropes, namely a tropological account by which the Latin past participle fatum is said to have come to designate that which must necessarily come to pass, i.e., fate, directly connects Leibniz's claims about the channel of tropes to the performative fiat by which God decides for this world. Leibniz's fatum example indeed touches on the very question of how the articulation of fate takes on force, changes actuality, and thus is not simply of constantively "about" what it decrees. In the channel-of-tropes account of fatum, however, a metonymy of cause-for-effect fills in for the performative moment, in such a way that obscures a clear view of the performative causality of fate. I argue that this obscurity and the indirectness of metonymy are not accidental, but are in fact required, i.e., there is no better or more direct way to represent the bindingness of God's fiat on the necessity of future events.