 Following the main line of al-Fārābī’s approach, Avicenna develops a more detailed discussion of the division of the sciences (Marmura 1980; Gutas 2003) according to which mathematical objects exist in the extramental world in association with determinate species of matter (e.g., wood, gold, etc.). Through the function of the faculty of estimation, mathematical objects can be abstracted in the mind from the specific species of matter they are attached to in the extramental world. Nevertheless, they must still be conceived as material things. In other words, mathematical objects in the mind are separate from determinate species of matter, though not from materiality itself (Avicenna [MPh]: chap. I.2; Di Vincenzo 2021: 20–27). Avicenna argues that numbers (aʿdād) and magnitudes (maqādīr)—as the most general representatives of the objects of arithmetic and geometry, respectively—are accidents (aʿrāḍ) and properties of physical objects existing in the sensible world (Avicenna [MPh]: chap. III.3–4). Neither numbers nor magnitudes have independent immaterial subsistence in the extramental world. Magnitudes (or geometrical shapes, to be more specific) cannot be detached from materiality even in the mind (Avicenna [MPh]: chap. III.4 sec.2 and VII.2, sec. 21). By contrast, numbers can be considered fully separate from matter and materiality. Nevertheless, such a consideration of numbers is metaphysical, rather than mathematical (Endress 2003: 142; Zarepour 2016: sec. 4). Numbers, inasmuch as they are subject to mathematical studies, must be receptive to decrease and increase. Therefore, even in the mind, they must be conceived as properties of material things (Avicenna [MPh]: chap. I.3, secs. 17–19). In sum, mathematical objects exist in the extramental world as the properties of physical things constituted of determinate species of matter. Mathematical objects can be abstracted from these determinate species of matter in the mind. But they must still be thought of as properties of material things. Otherwise, they cannot be the subject of mathematical studies. Avicenna’s discussion of the roles of the faculty of estimation and the process of abstraction in mathematical studies has been interpreted in two different ways. Some scholars (McGinnis 2006; 2017; Ardeshir 2008; Fazlıoğlu 2014; Tahiri 2016; 2018) think that mathematical objects are in the first place mental objects, and abstraction is a mechanism for constructing mathematical objects. Attributing a literalist view to Avicenna, some others (Marmura 1980; 2005; Zarepour 2016; 2021; McGinnis 2019) argue that mathematical objects literally exist in the physical world and abstraction is a cognitive process for grasping mathematical concepts, rather than producing mathematical objects. These different interpretations remind us of the contrast between the literalist (Mueller 1970; 1990) and the abstractionist (Lear 1982; Hussey 1991) readings of Aristotle’s ontology of mathematics. The most obvious objection to the literalist view is that, unlike physical objects, which are inexact and imperfect, mathematical objects seem to be perfect and exact (or idealized). For instance, it seems that there exists no perfectly circular physical object whose circumference is not (at least to a modest extent) serrated. To rebut this objection against the literalist reading of Avicenna’s ontology of mathematics, it has been argued that he endorses the existence of perfect mathematical objects in the physical world (Zarepour 2016: sec. 5; 2021: sec. 4).