In Islamic philosophy, Sufi metaphysics is centered on the concept of or . Two main Sufi philosophies prevail on this topic. literally means "the Unity of Existence" or "the Unity of Being." , meaning "existence" or "presence", here refers to God. On the other hand, , meaning "Apparentism" or "Monotheism of Witness", holds that God and his creation are entirely separate. Some scholars have claimed that the difference between the two philosophies differ only in semantics and that the entire debate is merely a collection of "verbal controversies" which have come about because of ambiguous language. However, the concept of the relationship between God and the universe is still actively debated both among Sufis and between Sufis and non-Sufi Muslims. Waḥdat al-Wujūd (unity of existence) The mystical thinker and theologian Abu Saeed Mubarak Makhzoomi discussed this concept in his book called Tohfa Mursala. An Andalusian Sufi saint Ibn Sabin is also known to employ this term in his writings. But the Sufi saint who is most characterized in discussing the ideology of Sufi metaphysics in deepest details is Ibn Arabi. He employs the term wujud to refer to God as the Necessary Being. He also attributes the term to everything other than God, but he insists that wujud does not belong to the things found in the cosmos in any real sense. Rather, the things borrow wujud from God, much as the earth borrows light from the sun. The issue is how wujūd can rightfully be attributed to the things, also called "entities" (aʿyān). From the perspective of tanzih, Ibn Arabi declares that wujūd belongs to God alone, and, in his famous phrase, the things "have never smelt a whiff of wujud." From the point of view of tashbih, he affirms that all things are wujūd's self-disclosure (tajalli) or self-manifestation (ẓohur). In sum, all things are "He/not He" (howa/lāhowa), which is to say that they are both God and not God, both wujud and not wujud. In his book Fusus –al-Hikam, Ibn-e-Arabi states that "wujūd is the unknowable and inaccessible ground of everything that exists. God alone is true wujūd, while all things dwell in nonexistence, so also wujūd alone is nondelimited (muṭlaq), while everything else is constrained, confined, and constricted. Wujūd is the absolute, infinite, nondelimited reality of God, while all others remain relative, finite, and delimited". Ibn Arabi's doctrine of wahdat ul wujud focuses on the esoteric (batin)