 Through the intellective process described, the active intellect makes the forms that are in matter progressively more immaterial and brings about the acquired intellect. Since the acquired intellect is of the same sort as the active intellect, the human intellect thus becomes progressively closer to the active intellect. In the view of al-Fārābī, this is precisely the ultimate goal and happiness (sa‘ādah) of human beings, and constitutes the way in which they attain definitive perfection: through the intellectual process the acquired intellect gradually becomes a substance that performs the action by virtue of which it realizes itself fully as substance and, in this way, remains in existence in the afterlife (hayāh al-ākhīrah) (al-Fārābī LI: 27; 31–32; LC: 219–220; OI: 75–76). Through this gradual process of perfection, the acquired intellect ends up acting only within itself, equating its own action with its own existence. When this stage is reached, the body is no longer needed as its matter in order to subsist, whereas it was initially needed for actions such as sensation and imagination to take place. Hence, the most perfect state the intellect can achieve is when it can subsist independently from the body. Nevertheless, the way in which al-Fārābī understood the relation between the acquired and agent intellects, was harshly criticized by Averroes who judged it impossible to conceive the transformation of the material intellect within the perishable human being into an immaterial and eternal substance at the level of the agent intellect (Averroes LCD: 387–388). 