 The human intellect can engage in a syllogistic process in the order which includes the middle terms and which is identical with that of the celestial intellects for the simple reason, as Avicenna repeatedly insists, that both human and celestial intellects are congeneric (mujānis), immaterial substances. However, their respective acquisition of knowledge is different because of their different circumstances: the human intellect comes into being in an absolutely potential state and needs its association with the perishable body in order to actualize itself, whereas the celestial intellects are related to eternal bodies and are permanently actual. Thus unfettered, their knowledge can be completely intellective because they perceive and know the intelligibles from what causes them, while the human intellect is in need of the corporeal senses, both external and internal, in order to perceive the effect of an intelligible from which it can reason syllogistically back to its cause. This makes it necessary for Avicenna to have an empirical theory of knowledge, according to which “the senses are the means by which the human soul acquires different kinds of knowledge (maʿārif ),” and man’s predisposition for the primary notions and principles of knowledge, which come to him unawares, is itself actualized by the experience of particulars (GS 12a, 23; transl. and analysis in Gutas 2014b-VII, esp. pp. 25–27). For human knowledge, therefore, the intellect functions as a processor of the information provided by the external and internal senses. It is important to realize that this is not because the intellect does not have the constitution to have purely intellective knowledge, like the celestial spheres, but because its existence in the sublunar world of time and perishable matter precludes its understanding the intelligibles through their causes. Instead, it must proceed to them from their perceived effects. However, once the soul has been freed of the body after death, and if, while still with the body, it has acquired the predisposition to perceive the intelligibles through philosophical training, then it can behold the intelligibles through their causes and become just like the celestial spheres, a state which Avicenna describes as happiness in philosophical terms and paradise in religious.