The Classification of Medicine in Somme Commentaries on Avicenna’s Canon The intrusion of philosophy, and particularly physics and logic, into medicine goes back at least to Galen for whom the best doctor was a philosopher who was able to infer a sound judgment out of the empirical data. One of the loci in which this interdependence is the most intricate is the theory of the elements that bears a tremendous influence on medicine through the primary qualities on which humoral pathology rests. However in the first pages of the Canon, Avicenna drew a strict line between physics and medicine, considering the latter as an independent science with its proper object, though subordinated to the science of physics from which it draws its principles without being able to demonstrate them. Therefore, Avicenna contends, it is qua philosopher and not qua physician that Galen must have demonstrated the number of elements. In this paper I will examine the responses to that particular point by some of the most emblematic commentaries in the vast, and as of yet untapped literature which grew around Avicenna’s Canon at the turn of the 13th century and beyond. I will explore first how the epistemological question of the priority of physics over medicine fits into the recurrent Aristotelian theme of the priority of one science to another as it is mainly addressed in the Posterior Analytics. I will then turn to Fakr al-Dîn al-Râzî’s critique of this issue in his commentary on Avicenna’s Kulliyyât, the response of his disciple Afdal al-Dîn al-Khunajî (d. 1249), in his Shar? Kulliyât al-Qânûn and the vehement critique of ?Abd al-Latîf al-Baghdâdî in The pages [he] composed on the book of Mu?ammad b. ?Umar, known as Ibn khatîb al-Rayy, composed on some of the first part of the Canon .... What is at stake is not a mere debate between theory and practice, but a theoretical reflection upon the relationship between on the one hand the contingent, specific and factual object of medicine and on the other, the more universal principles of physics on which medicine depends to prove its own conclusions without being able to submit them to rational inquiry. Ultimately it is the status of medicine which is at stake, and its capacity to question the physical principles on which it is grounded.