Mullā Ṣadrā, in a discussion like the relationship between the constant and the changing, insists on constancy of the change and says that the movement is something that its being changed is identical with constancy: because everything – whatever that may be – is of constancy, although its constancy be merely constancy in being changed. In other words, there is something constant in the changing things and the changing is constant in its own changing. Thus, the changing things are related to the constant from the very constant aspect. He sometimes considers this constancy as a kind of four–dimensionalism and does not regard this four–dimensionalism to be inconsistent with presentism. Now, this important problem appears that how much the paradoxical expressions such as “constancy of the change” and ‘combination of four–dimensionalism with presentism’ are acceptable. The main purpose of the essay is to critically study the very Ṣadrian version of constancy of the change in the constant–changing relation and similar discussions. We will see that Ṣadrian commentators have had different reactions to such expressions as constancy of the change: Some, like ʻAllāmah Ṭabāṭabāyī, have accepted it and some, like Muṭahharī and Miṣbāḥ Yazdī, have not. The criticism of Muṭahharī and Miṣbāḥ Yazdī, shortly speaking, is the claim that constancy of the change is abstract and mental property not external one and that it is conceptual not extensional. We will continue to criticize the evaluations of Muṭahharī and Miṣbāḥ Yazdī: if there is not some kind of constancy in the external world as the truth–maker, our mind cannot apply the concept of constancy about the external changings. Finally, we will focus on the logical structure of the discussion in our special critique of constancy of the change to show that Ṣadrian version of constancy of the change is not merely a paradox but arguably a real contradiction. The reason is that, if the logical structures of (A) “the changing in its own changing is constant (and not changing)” and (B) “the changing in its own changing is not constant (but is changing)” are new logical structures such as (C) “x in its own being x is not x” and (D) “x in its own being x is x”, then it is resulted that (B) “the changing in its own changing is changing (and not constant)” to be true and therefore a controdiction to be appeared: both (A) and its contradictory, (B), are true. So, there is something in the material world that is controdictorily both constant and changing – while such resolutions as the difference in aspect are not applicable in the case of this contradiction. But, if, on the contrary of Ṣadrian Philosophy, we consider constancy of the change merely as an external time permanence and does not confuse this time permanence with real constancy, there will not emerge the non–material constancy contradictorily from this intensity of the change.