Although duality of soul and body has been ingrained in minds of general public and was prevalent among most philosophers before Sadra, robust foundations that Sadra laid in his soul psychology have compelled nearly all contemporary philosophers to negate this duality. However, a form of dualistic thinking still persists. It seems that MullaSadra's well-known view, namely union (ittihadi) of soul and body, is a justifiable perspective in describing their relationship. However, Sadra's ultimate view in ontology, which is the theory of the unity of personal existence, necessitates that all issues of Transcendent Philosophy, including topic of soul and related matters, be justified and interpreted based on this viewpoint, which is considered one of the innovations of present article, in terms of approach. In this article, relationship between soul and body in Islamic philosophy is presented in two general categories: dualism and monism. Subsequently, within monistic viewpoint, which refers to perspective of followers of Transcendent Philosophy, opinions are categorized into two groups: those who believe in "union of soul and body" and those who believe in "unity of soul and body." The content of the latter section demonstrates that there are abundant indications for justifiability of monistic viewpoint. Content innovations of the article, which are considered to be a content representation of relationship between soul and body based on unificationist perspective, include: 1) Constructing unity of soul and body based on defining body as intrinsic act of soul; 2) Determining an indicator for recognizing real body as belonging to soul possession through analysis and decomposition of concept of possession; 3) Providing a governance interpretation of soul and body unity through sameness of body's corporeality with lordship and management; 4) Presenting an anti-materialist interpretation of soul-body unity based on theory of soul physicality and analytical plurality between Material and face.