This chapter orients the reader to the ideas of multiplicity in Badiou's and Deleuze's work, and to the ontological paradigms these ideas support. I acknowledge a conceptual debt both programs owe to precedent uses of Mannigfaltigkeit (manifold, multiple), particularly in Kant's discussion of the manifold in the Critique of Pure Reason. This chapter also presents my method for slow comparison—allowing the programs to be articulated on their own terms before turning to any critique—as facilitated by this moment in reflection on the debate; I also show that my own method is an alternative to the paradigm of martial opposition that characterizes much of the conversation so far. I conclude by offering a plan of the text.