 Avicenna divides “actual” beings, as opposed to impossible things, into necessary in itself and possible in itself but necessary through another (Davidson 1987: 292–3; McGinnis 2010: 159–164). The necessary in itself is that which has existence in its essence and an impossibility arises whenever it is assumed not to exist. By contrast, the possible in itself but necessary through another is that which “has no existence in essence” and “no impossibility” arises whether it is assumed to exist or not (Avicenna al-Najāt: 546; cf. al-ʾisharāt: 122; cf. al-Ghazali Maqāṣid: 100–101). In other words, both existence and non-existence are equal states with respect to it. This latter point is crucial to Avicenna’s proof, for it stipulates that there must be an external cause that ultimately preponderates existence over non-existence in things that are possible. This cause must be necessary in itself. Considering all possible things as an “aggregate” (jumlah), two alternatives arise in regard to the cause of that aggregate (Avicenna, al-Najāt: 567–8): either the aggregate of possible things is self-caused or caused by something external. Avicenna dismisses the former alternative as impossible because the nature of what is possible in itself does not change independently of a cause; possible things become necessary only through other causes. Hence, an aggregate of possible things is also possible in itself and cannot be self-caused. Furthermore, “a chain” (silsilah) of possible things cannot continue ad infinitum and it must end to a being that is necessary in itself. The trait of “necessary existence” further entails a number of divine attributes such as oneness, simplicity and goodness, which permits identifying the Necessary Existent with the deity (Adamson 2013: 172).