As for the term “plural,” this very word is understood and recognized only through the notion of multiplicity. When we say that multiplicity is what is counted by means of the unit, we have already brought unity into the very definition of multiplicity, and with it we have also introduced number and measurement—both of which are themselves grasped only by reference to multiplicity.

Hence it scarcely profits us to put forward any definitive statement on this matter. Yet it would seem that multiplicity is, in fact, more familiar to the imagination, and that both unity and multiplicity are among the notions apprehended intuitively. When multiplicity is mentioned, we first picture it imaginatively, whereas unity is understood without any prior imaginative starting point—resorting to the imagination only when unavoidable. Thus, defining multiplicity by appealing to unity is an intellectual definition in which we take unity as an idea conceived in and of itself. Conversely, defining unity by way of multiplicity is merely an indication—employing a purely imaginative, almost dreamlike method—that points us toward an intelligible meaning not presently pictured in the mind.

Accordingly, when they say that unity is “the thing in which there is no multiplicity,” they show that the term refers to the self-evident concept in our minds that stands opposite to multiplicity; they point to it by denying multiplicity of it.

What is truly astonishing is the position of those who try to define number by saying that number is a multiplicity composed of a unit or of units. Multiplicity itself is number; it is not a genus of number. The reality of multiplicity is that it is composed of units. Hence to say that multiplicity is composed of units is no different from saying that multiplicity is multiplicity, for multiplicity is nothing but a name for what is composed of units.