distinction of the predications from the perspective of semantic developments of "predication"

in dealing with uninvited guests as natural propositions and propositions that are based on primary essential predication, the term “predication” has undergone some semantic changes; according to the elements of “unity” and “difference” three periods may be distinguished: (1) the period in which “what causes the unity” is external and “what causes the difference” is in the mind, (2) the period in which “the unifier”, in addition to its being in the outside world, may be in mind too and “the differing factor”, also, moves to the top level of mind or another mind, (3) the period in which “the unifier” and “the differing factor”, besides in viewed and viewer, may regularly be located in viewer and viewed. without separating these periods, the theory of “distinction of the predications” in mulla sadra’s works cannot correctly be read. in this article, in fact, “what causes the unity” and “what causes the difference” will be analyzed in a historical development so that some parts of obscurities about this theory may be removed.