Does self-knowledge originate from our body and external characteristics or are the internal characteristics, human and individual characters involved as well? How do others know us? What are the shared criteria of self-knowledge and knowing others? It is here that self-perception is related to self-knowledge and the perception of “other”. In this article in addition to the above questions, we are going to answer the following questions: if, for example, we accept the principle: “existence is perception” (Esse est percipi) or if, we accept Barkley’s view that existence is “the thing perceived” then what is “I” and “self” when we say “I have right” or “This is mine” or “I know myself”? Whether we reject the existence of “matter” believing in appearance or appearance without reality, or accept the existence of matter and materialism believing in body in the shape of human body as his being and existence, we must, prior to this, show where to predicate the “right” belonging to “I”. Which schools of thought and scholars have put forward “I”? And is it possible to define it philosophically?