In this article, by an introduction about the importance of recognition of existence, I proceed to existence as a common subject between philosophy and gonastism. The subjects of existence is the most obvious concept and also the most comlex fact in metaphysics. In this article also pointed to the Molla Sadra"s views about the existance and his several profound questions about the significance and recognition of existence... seven reasons from the last chapter of Tahrir -al- Tamhid and reasonof piouses has been explained briefly. Another part of this article is the viewpoints of professor Assar about existence and Ayatolah Rafiee Ghazvini about the EXISTENT unity. This article is an introduction to the proposal of research about Ibn Arabi and late Imam Khomeyni" s viewpoints which we are going to explain them later.

Although the philosophical system of Ibn Sina is a purely intellectual one that many of its underlying principles is constituted by the principles of Aristotelian philosopy and his philosophy is called "peripatetic philosophy", but Ibn Sina never commits himself to the preservation of all the principles of Aristotelian philosophy and in many cases criticises them. By accepting some Aristotelian principles and presenting his own philosophical principles, Ibn Sina is considered the founder of Islamic prepatetic philosophical system which is a philosophy based on EXISTENT.He regards the object of his metaphysics EXISTENT qua EXISTENT and founds his metaphysical principles of the basis of that concept.Throughout the history besides Ibn Sina many of the philosophers after him as well in the Islamic world and in the west consider the object of metaphysic as EXISTENT qua EXISTENT, but it does not mean at all that all these philosophers have a single metaphysical structure. In the philosophy of Ibn Sina EXISTENT is a univocal concept which by anological gradution applies to its exemplifications. The concept of EXISTENT qua EXISTENT is so universal and comprehensive that all the objects in the universe are the extentions and denotations of it.The wide scope of EXISTENT qua EXISTENT include all creatures, from the blessed and exalted God to abstract possibilities and then corporeal possibilities and at last at the lowest level of existence, the primary matter.Among these EXISTENTs God has a pure self subsitent existence, depends on no other being and by contrast possible being have a correlative and dependent existence on neccessary beings and in their existence and survial need neccessary being.

Generally speaking, Islamic philosophy is the legacy of Greece and is modeled on Aristotle's works in particular. Like the collection of his philosophical works, it consists of logic, general metaphysics, physics, theology, and practical wisdom. Concerning the definition and subject of philosophy, following the Aristotelian tradition, Islamic philosophy has referred to "EXISTENT qua EXISTENT" and "separate substances" and posed the discussion of whether each is separately the subject of philosophy, and whether they are the same as each other or one includes the other. Moreover, it asks how, if the former is true, this sameness is justified, and if the latter is true, which is general and which is particular.In all the philosophical systems of the East and the West, these two issues, that is, the accidents of EXISTENT qua EXISTENT and separate substances are mixed with each other and cannot sometimes be separated from each other. However, in Islamic philosophy, particularly after Mulla Sadra, they were separated from each other under the titles general theology and particular theology or theodicy. However, both are subcategorized under the all-inclusive title "prime philosophy" or theology. There have also been debate concerning the scientific borderlines between the two issues; nevertheless, they have not led to any conclusions in practice. This paper deals with a methodological demarcation between them.

The problem of self- evidency of existence has been propounded in a content contrary, or at least unconcerned, to the theory of the reality of existence. But some scholars such as Riizl or Tusl have claimed self-evidency of EXISTENT. EXISTENT here has been interpreted as EXISTENTiality. If we accept the reality of existence and notice that this reality could not be found in the mind, we can conclude that we can only understand the implications of the EXISTENT not its reality. Its reality can be understood only in the Knowledge by presence. Knowledge by presence is not divided to concepts and propositions. So the meaning of self- evidency of existence is the self- evidency of existence's implications.