Ibn Sina (Avicenna 980-1037 AD) presents his metaphysical framework in the treatise Ilāhiyyāt of Kitāb al-Šifā’ (known in English as the Metaphysics of the Book of the Healing or the Book of the Cure), in which:
- Existence is separated being (a thing), the latter is named quiddity (or essence). We can comprehend the quiddity of a thing without knowing anything about its existence.
- Things can be material singulars – sensibles, externals to the human, and concepts in the human mind. The corresponding mental and external existence is on the par for Ibn Sina.
- A thing is a composition of existence and quiddity.
- The necessary existent is it’s own existence, and as such is necessary; all the other things are contingent.
as presented in the OntoUML diagram below:
|“the Necessary Existent has no essence or no quiddity that differs from existence (anniyya) and is therefore beyond essence. The first attribute of the Principle is ‘that It is and that It is existent’ (inn wa-mawǧūd): existence is not what It ‘has’: It simply is […] absolutely necessary and simply coincides with, or more exactly, is Its own existence… The Necessary Existent has no cause. It has relations in so far as it is existent. […] the ‘thing’ in question is only necessary existence, it has no quiddity (or no quiddity beyond its existence) and is not, properly speaking, a “thing” (Bertolacci 2012a): in this case, in fact, what is revealed is the existence of the Necessary Principle, which is pure existence on condition of not and can therefore be conceived beyond essence and thingness.” |
Necessary Existent is also referred asFirst Principle.
|is its own Existence|
|Existence||Existence (al-mawǧūd) can be: mental, external, and the existence of the Necessarry Existent. Existence and being (a thing) are distinct.|
“Avicenna posits a distinction between the being of the thing and its existence. Clearly, then, the fundamental and primary character of being does not imply simplicity: to exist means to be a given entity in the world or—as Avicenna also uses it—a ‘thing’. The existence of something must thus be distinguished from its being what it is.” 
|“everything that is conceived of or simply mentally represented exists and hence has at least a mental existence (which means either intellectual or imaginary or estimative). Indeed, the existent as such is immaterial and only non-existence in the absolute sense does (obviously) not exist, since it cannot be either conceived or discussed” (Lizzini, 2019)||descendant of Existence; characterizes Concept|
|External existence (fī l-ʿayān) is existence in concrete material singulars.||descendant of Existence; characterizes MaterialSingular|
|Quiddity||Quiddity (māhiyya), essence or thingness is independent of existence, and necessarily accompanies the thing, be it particular or universal.|
“the quiddity or essence of a thing is not in its turn a thing” with its own mental existence so that, once added to (real) existence, it could become a real thing… What Avicenna states by distinguishing quiddity and existence is that quiddity does not coincide with its existence: neither with its mental existence, which is related but does not correspond to universality, nor with its concrete existence (fī l-ʿayān), which implies individuality… The indifference of quiddity to any kind of existence and determination truly establishes the correspondence between reality and knowledge: it is exactly because quiddity is in itself neither real nor mental that it can be present both in reality and in the mind, accompanied by the determinations of either individuality or universality: in concrete reality there is x in its particular existence, while in the mind there is x with its possible multiple predication. In this respect, the consideration of quiddity in itself—which corresponds to the thing in itself as expressed by its definition—transcends both levels of existence (external and mental) and in one passage is equated to the “divine existence” (wuǧūd ilāhī) of something that depends on God’s providence.”  E.g. “horseness” (which is common in the concept of the horse, and in Tucker, the horse).
|is shared part of the Thing, Concept and MaterialSingular|
|Thing||“In every thing the distinction between what the thing is and the fact that it is is inevitable. Existence can consequently be said to be external to essence, so that an existing thing, whose essence or quiddity is possible, can be said to be composed of essence and existence. […]|
In order to ask what a thing is, one cannot avoid referring to being, which is exactly what allows us to conceive all things, whether they are sensible, imaginary or intelligible, as existent. 
|Concept||Concept is the understood quiddity of things.||Exclusive part of Mind|
|Universal||Universal is the concept in the mind related to a material singular: “the one concept is related by the mind to many, and in this way it is universal”. |
“And the soul itself also conceptualizes another universal which unites this form with another one in this soul or in another soul; but all of them, insofar as they are in the soul, have a single definition.” 
|MentalExistence and Quiddity are parts of it|
|FictionalBeing||“the natures or quiddities of even such fictional beings as phoenixes and unicorns do indeed exist, although they have only a mental, and not a concrete, mode of existence” ||Is subkind of Concept|
|MaterialSingular||Material singulars are are concrete, external things.|
E.g. horses like: Lilly, Tucker, Spirit
|Is descendant of Thing|
|Human||A human person||Subkind of MaterialSingular|
|Mind||A human mind||exclusive part of Human; subkind of MaterialSingular|
|Modality||Modality “explains the relation that what exists has to its own existence: an existent [thing] can be either necessary in itself (ḍarūrī; wāǧib: it is then also necessarily one) or possible (mumkin, contingency) in itself”  – this is the case of every existent with the exception of the Necessary Existent.|
|Necessity||Necessity||characterizes NecessaryExistent; descendant of Modality|
|Contingency||Contingency or Possibility characterizes the Thing: it is possible for the quiddity of the thing to gain existence and also not.||characterizes Thing; descendant of Modality|
- All citations from: Lizzini, Olga, “Ibn Sina’s Metaphysics”, The Stanford Encyclopedia of Philosophy (Summer 2019 Edition), Edward N. Zalta (ed.)
- Raja Bahlul, “Avicenna and the Problem of Universals”, Philosophy & Theology 21
First published: 01/08/2019
Updated: 01/01/2021 added Human, Mind, Concept, FictionalBeing