In modern mathematics, numerous kinds of “numbers” have been identified, such as natural numbers and integers, rational and irrational numbers, algebraic and transcendental, real and imaginary, complex and quaternions, cardinal and ordinal, finite and infinite, infinitesimal and infinite, and thousands of other types. What would the analysis of these categories of numbers be within the framework of Aristotelian-Peripatetic philosophy? This paper aims to examine and analyze the first category—namely, natural numbers—based on the foundations of Aristotelian-Peripatetic philosophy. I begin by addressing the debate between Avicenna and Suhrawardī concerning the existence of numbers in the mind or in the external world, and I show that Avicenna’s position is correct, and moreover, that these two views can be reconciled. In the next step, I demonstrate that the disagreement among the Peripatetics over whether zero, one, and two count as numbers is a verbal dispute, stemming from different definitions of “number.” Then, inspired by a Fregean insight, I argue that Aristotelian discrete quantity and natural numbers, contrary to the dominant Peripatetic view, are second-order predicates or properties (i.e., secondary intelligibles [maʿqūlāt thāniyah]), and hence Suhrawardī's position and that of his followers is closer to the truth in this regard. Incidentally, by interpreting iʿtibārī concepts and secondary intelligibles as “accidents of accidents,” one can provide an interpretation of Suhrawardī that is compatible with Avicenna’s view on the extra-mental existence of numbers. Finally, I attempt to explain five essential features of natural numbers and, with their help, arrive at a formal and reliable definition of the general concept of “natural number.”