Abstract

This chapter investigates the Neopythagorean roots of Plotinus’ concept of number. Porphyry’s reports of Plotinus’ use of Neopythagorean sources in his teachings are quickly confirmed in the Enneads. In addition to Numenius’ influence on the definition of multiplicity as “separation,” this chapter reveals the programmatic significance of Moderatus’ distinction between the monad as the principle of numbers and the one as the principle of enumerated things on Plotinus’ two kinds of number. This discovery also shows Plotinus’ use of Moderatus’ definition of mathematical number in the formulation of the outward and inward directions of multiplicity. Next, the chapter examines the elements from Nicomachus of Gerasa’s Introduction to Arithmetic in Plotinus’ concept of multiplicity. The final conclusion of the chapter shows that Plotinus views multiplicity exclusively as number, which preserves it from dissipating into infinity and thus non-existence.