 Even if this extended conception of a human being is allowed, that still leaves a question about why these two separated intellects must each be singular, and so shared by all human beings. Ibn Rushd’s answer depends in part on an argument against private concepts: that without concepts that are literally shared, teachers could not convey knowledge to students (LongAnima III.5 {411–12}; Ogden forthcoming). He also argues that an intellect individuated by a corporeal subject would receive individualized forms (LongAnima III.5 {402}; Ogden 2016). Accordingly, he thinks the domain of actually intelligible concepts, and of the intellects in which those objects exist, must be entirely separate from the material realm, and cannot be individuated by matter. And, as we have seen in the previous two sections, he is for independent reasons committed to the existence of such a realm, among the celestial spheres. Accordingly, the human intellectual powers can be identified as the lowest members of this hierarchy (LongAnima III.19; Davidson 1992, 223–31; Taylor 1998).