 Other properties (see Ilāhiyyāt, I, 7) are attributable to a being necessary in itself: unity, simplicity and then non-relativity, immutability, non-multiplicity and non-association with anything other than itself (these properties, among others, are discussed in terms of negative attributes—ṣifāt—of the Principle in Ilāhiyyāt VIII (4, 347, 10–348, 6; 5, 354, 9–14). The various and complex justifications Avicenna uses in this respect are all reducible—as he himself observes (Ilāhiyyāt, I, 7, 46, 4–5)—to a single general line of argumentation, which shows that two supposed necessary beings could not be distinguished one from the other: if they were to be distinguished by virtue of an essential property, they would be essentially different and therefore both not necessarily existent in themselves; if they were to be distinguished by virtue of an accidental property, they would imply the existence of an external cause and would be equally—each of them—not necessary (Ilāhiyyāt, I, 7, 43, 4–46, 5; 46, 6–47, 5).