This may be explained in several ways.
One of them is as follows:
It has been established that Allah is eternal in Himself, necessarily existent in Himself, self-subsisting by Himself, and Creator in Himself, along with His other unique attributes. The well-known argument for necessary existence applies equally to all these meanings.
Thus, it may be said:
“Existence is either necessary or contingent, and the contingent must have a necessarily existent cause. A necessarily existent being must therefore be affirmed in either case.”
This is analogous to saying:
“An existent is either eternal or originated, and the originated must have an eternal cause. Thus, an eternal being must be affirmed in either case. An existent is either self-sufficient or needy, and the needy must have one who is self-sufficient. Thus, the existence of one who is self-sufficient must be affirmed in either case. An existent is either self-subsisting or not self-subsisting, and that which is not self-subsisting must have one who is self-subsisting. Thus, the self-subsisting must be affirmed in either case. An existent is either created or uncreated, and the created must have an uncreated Creator. Thus, an uncreated Creator must be affirmed in either case.” There are numerous analogous arguments.
It is then said:
“With regard to this necessarily existent, eternal Creator, is it possible for Him to possess perfection that contains no deficiency and whose existence is possible, or is it not?” The latter is impossible, for such perfection is possible for an originated, needy, contingent existent. It must therefore be possible, with even greater reason, for the necessarily existent, self-sufficient, and eternal One, since both are existents. The discussion concerns perfection whose existence is possible and which contains no deficiency.
If a perfection whose existence is possible can belong to that which is inferior, then it can belong with even greater reason to that which is superior. For if it is possible for that which is deficient in its existence, then it is all the more possible for—