Rationality is the most prominent action and characteristic of humanity that different schools of thought and philosophy see their reputation and survival in attribution to it. This article seeks to answer this question which how the Transcendent Wisdom as the highest symbol of Shi'ite rationality to draw basic conditions of just thinking and wise intellection and it is based on what elements? And to achieve truth and open up bright horizons facing humanity it recommends the intellectuals observing what principles?
By examining the works of Mulla Sadra it is obtained that he emphasizes on the principles and rules, not as only ethical and guidance advices but as scientific and reasoning necessity, that it is inevitable to observe them and achieve facts and discover the new horizons for obtaining a larger world, that some of these principles and rules such as reason – pivot, faith, being arcuate, wisdom, freedom, cleaning up the appearance by Shari'a and purity of heart from inappropriate thoughts are positive and proving criteria, and its usage in various areas of reflection is essential, that they are interpreted "the necessities of rationality" in this research. Some of other principles and rules such as inherent defect, impurity of gem of life, away from favorable end, fallen wearing and unawareness of favorable way are nonpositive that abstinence from them is essential, and they are interpreted "the barriers of rationality".