 Most Muslim thinkers who have talked about the epistemology of mathematical concepts believe that these concepts are formed through some cognitive mechanisms whose first input is the data we receive through our external senses. The details of such mechanisms are spelled out in different ways by different philosophers, depending on their general picture of human cognitive psychology. For instance, Avicenna puts forward a thought experiment showing that no mathematical concepts can be grasped in the absence of sense perception (Avicenna [MPh], chap. VII.3, sec. 1; Zarepour 2019: sec. 5; 2021, sec. 3). This indicates that Avicenna endorses some sort of concept empiricism about mathematics. On the literalist interpretation of Avicenna’s ontology of mathematics, mathematical objects exist in the sensible world as non-sensible connotational attributes (maʿānī) of physical objects. Like all other connotational attributes, mathematical entities are perceived by the faculty of estimation. For instance, it is the faculty of estimation which perceives two-ness when we see two books. In such an experience, the sensible data collected by the external senses would be transferred to the faculty of estimation through the mediation of the faculty of common sense (ḥiss mushtarak). Estimation enables us to overlook all other characteristics of the experience we have had and to perceive two-ness that is not directly accessible to our external senses.