 This is probably due to the emphasis of Avicenna and al-Fārābī on the role of estimation (wahm) in conceiving mathematical objects that, in post-Avicennian philosophy, mathematics is often referred to as an estimative (wahmī or mawhūm) science (Pines 1974). Before or contemporary with Avicenna, many Muslim thinkers had emphasized that mathematical objects exist, in one way or another, in the physical world. For instance, in The Book of Instruction (Kitāb al-tafhīm ([Instr]), al-Bīrūnī (d. ~1048) defends an account of the nature of mathematical objects which seems to have strong affinities with the literalist reading of Avicenna (Samian 2011; 2014). In the same vein, Ibn al-Haytham (d. 1040), in the first pages of his Resolution of Doubts (Ḥall shukūk, [Doubts]), argues that geometrical objects exist in the sensible world. They can be abstracted from matter through the activity of the faculty of imagination (takhayyul), whose function in Ibn al-Haytham’s theory of mind is very similar to the function of estimation in Avicenna’s psychology. However, by contrast with Avicenna and Aristotle (De anima 428a5–18), Ibn al-Haytham thinks that imagined forms, that are abstracted from physical objects, have a more real existence. For him, the real (ḥaqīqī) existence of mathematical objects is instantiated in imagination and distinction (tamyīz)—another cognitive faculty in Ibn al-Haytham’s philosophy of mind, which plays a crucial role in grasping universal concepts through the mediation of imagined forms. (See Ighbariah &amp; Wagner 2018: secs. 79–81. R. Rashed [1993: 2:8–19] believes that there were two different Muslim thinkers named ‘Ibn al-Haytham’. Sabra [1998; 2003] rejects Rashed’s view and here I follow Sabra’s position.)