FARABI has dealt with the existence and whatness of limit from two perspectives of logic and philosophy and evaluated its epistemological aspect meticulously. Beside the term limit, he has also used some other words such as description, definiens, particular accident, and definition, each of which carries several meanings and, at the same time, indicates an acquired notional perception.He explains the different meanings of limit, its kinds, levels, and component parts, as well as the mode of the commonality of some limits with demonstration. Concerning the acquisition of limit, FARABI presents his own innovative method and then refers to and criticizes the three methods of early philosophers. He believes that a limit that is attained through the approach of the human spirit to the world of creation does not portray the realities of possible things, is not a form including the essential features of an object, and does not reveal its quiddity. Rather, it is a knowledge that merely manifests the attributes and accidents of objects because it is based on sense perceptions. If the soul is polished with the theoretical intellect and faces the world of command, the divine intelligibles will be printed on it in the light of the divine emanation and the real limits of objects are discovered. He has frequently and explicitly said about the essence of the One that there is no limit for Almighty Truth, Who is the Absolute Being, and thus it is impossible to attain His reality. However, man possesses a primary and non-acquired knowledge of the necessity of His Existence through whichthe knowledge of His other attributes is possible for him.