   The middle ventricle is the location of the next pair of internal senses, as Avicenna first conceived them. They comprise a novel faculty of “estimation” (following the Latin aestimatio), wahm in Arabic; and a second, chameleon type faculty. It functions both imaginatively (in animals and humans), and rationally (in humans alone). As another aspect of the imaginative faculty, Avicenna calls it simply al-mutakhayyîlah, “the imagination,” but due to its function it is known as the “compositive imagination.” However, when this faculty deals with specific, materially based concepts, Avicenna calls it qûwah mufakkirah, a thinking or “cogitative” faculty.