 The core of the distinction is that what is necessarily existent is purely existence (but not undetermined common existence) and is indeed the Necessarily Existent Principle. Conversely, everything that does not exist necessarily and therefore has a possible relation to existence is something that is possible, so that in order to exist it always and necessarily refers to a cause that makes it exist: a cause that justifies the fact that instead of being possible (mumkin) and therefore not already assigned to existence, the thing is qualified as existent. Non-determination to existence leads to non-existence (ʿadam, lays, laysa) and this is in fact what pertains to the thing in itself. Existence—or more precisely a determination of its relation to existence—pertains to the thing because of something else (the cause). In this respect, non-determination coincides with possibility, whereas determination coincides with necessity per aliud. In ontology, the logical notions of the possible and the necessary become the duo of what is “necessary in itself” and what is “necessary by virtue of another” (Naǧāt: 547–549; Lizzini 2011: 116–132).