Not extant though what is presumably a similar argument can be found in al-Qānūn fī al-Ṭibb (Bk. I, Pt. 2, Thesis 2a, Chap. 8). Ibn Sīnā’s position, that the equatorial region is the most temperate, was criticized by Bīrūnī, Fakhr al-Dīn al-Rāzī, and Naṣīr al-Dīn al-Ṭūsī. See Ragep, Ṭūsī's Tadhkira [1993], 1: 256-9 and 2: 473.