Plato's Theory of forms is one of the most controversial philosophical theories. With this theory Plato tries to establish a rigid and solid basis for intellectual knowledge. But his theory leads to an implausible gap and separation between the intelligible and sensible worlds. Aristotle, as the first critic of Plato's theory, disagrees with different aspects of his theory, especially the separation it leads to.Mulla Sadra in the history of philosophy is the first philosopher who could remove the separation and gap between the sensible and intelligible world. According to his philosophical bases, the intelligible and sensible entities are two levels of one reality which is the reality of existence. He also denies the Platonic theory of preexistence of human soul. Hence, unlike Plato, he interprets human knowledge as a kind of establishment not remembrance.