In the ontology presented by the Quran, existence is known as a truth of gradation, essential order and inseparability so that its lower grades are degraded and exemplified orders from its higher grades. The latter are known as the unseen qualified with stability, unchangeable nature and longitudinal relation of absoluteness and limitation; the reality that descends from high grade as manifestation. The Holy Quran, as the manifestation and appearance of the knowledge of God, the Exalted, also has such an identity; the Qur'an, therefore, has a material and visible existence and, at the same time, a lighted and invisible existence of which the latter is known as the essence of the holy Quran, the fact being of grades. Such phrases: Umm ul-kitab, kita ul-maknoon, louhi mahfuz and kitab um-mobin in the Holy Quran refer to each of these levels. This research seeks to explain the principle of the Quran's state of being gradational on the basis of reasonable and traditional proofs with an emphasis on Allamah Tabatabai's exegetic view.