To Aristotle, the passive intellect in the human soul is potential, and it becomes actual through an intellect that is an active cause. This intellect, that is, the active intellect corresponds to actuality and thinks perpetually;  is separate, immortal, and eternal. From this aspect, it seems as an intellect external to the soul. However, Aristotle does not express clearly this matter. On the other hand, when it is assumed that the active intellect is external to the soul then the question regarding what it corresponds arises. It is not possible to answer the question precisely within the framework of Aristotle’s explanations. As Aristotle does, Al-Kindi also points out that the intellect which is found potentially in the soul comes into actuality through another intellect, that is, the perpetually actual intellect; thus he calls the intellect in the actuality as “the acquired intellect”.  However, Al-Kindi adds to the intellects another sort called “the emergent/appearing intellect”, and this intellect corresponds to the manifestation of the knowledge in the soul. Although Al-Kindi regards the intellect that is perpetually actual as universals, he does not give comprehensive explanations about his arguments. A case of uncertainty like the one in Aristotle, consequently, preserves its existence. Thus the article defends that Al-Kindi's account also falls short of providing an explanation that avoids the problems which emerge in the Aristotelian account.