Transcendent Philosophy provided us with three ways for dealing with the epistemologically explanation of causality: the first way in the subject of knowledge, the second in the object of knowledge, and the third in the knowledge itself. In the subject, according to Sadra’s philosophy, soul is united with body and its faculties in the manner of ‘status restricting regard,’ but even has an existential unity with it, So that the problem of soul-body duality resolves, and soul connects directly with the world and perceives it. In the object, according to Sadra’s philosophy again, philosophical truths like necessity, causality, unity, actuality, etc. are united with external existence and objective reality in the manner of ‘condensation restricting regard,’ but even they have existential unity, so that the human knowing apparatus directly perceives it. And in the knowledge itself, according to Sadra, the cognition is existential, not quidditative, so that it could connect the knower and known and explain them. According to this substantive change in Sadra’s philosophy, reason directly perceives and intuits rationally the causality in the sensual perception and intuition itself, and in another stage abstracts it.