 This definition is based on the famous division of the arts into what belongs to the sphere of necessity and what belongs to the sphere of possibility. The art of medicine does not belong to the sphere where consequences follow actions necessarily, as with arts like carpentry. In medicine, even if the physician acts based on scientific principles, the intended end does not necessarily follow. As he puts it, “Apparently, we do not have any of the premises that bring us certainty in many of these pursuits. But even so we must try, insofar as we are able” (Kulliyyāt II.208). The practical dimension of medicine is similarly central to his commentary on Ibn Sīnā, which begins with Ibn Sīnā’s statement that “Medicine is preserving health and curing disease,” and comments: “This is the definition of medicine, and its completion would be to say that medicine is an art whose action is preserving health and curing disease, based on science and experience” (CommIbnSīnā 46; see also Kulliyyāt prol.131). As one may notice, Ibn Rushd insists on acting in both texts.