It was Mulla Sadra that could bring a coherent philosophy...

It was Mulla Sadra that could bring a coherent philosophy that can have the advantage of mystical thought along with demonstrations that satisfy logically all who think of rational acceptance. He achieved a changing point in philosophy in the light of importance of existence in mysticism. This changing point was "fundamental reality of existence" or "principality of existence" that refers to the truth of existence not its notion.

All philosophers before him had based their ideas on the different conditions of quiddity or thing-ness which means the anticipation of quiddity to the existence that, in their views, is regarded after categorical explanation of all things. If we consider truth of existence in every thing prior to its quiddity (thing-ness) as only fundamental real, then every philosophical explanation will change.

He has argued for this important philosophically changing point then he has examined, deeply, all other philosophical subject in the light of this principality of existence. Therefore, all philosophical studies like causality, change and movement, unity and multiplicity and etc. would have new and deeper meaning by acceptance of fundamental reality of existence. In the light of principality of existence we will have a new philosophical perspective of the world that is deeper and more real.

In this light we will have the vision of occupation of real world only of existence and nothing else. All other meanings arise from this vision and they should have their fundamental reality in this light. If we may think in this manner we do not think of meaning of existence (like what happened in ontological argument) but we encounter the truth of existence. This truth is quite different from all starting point in Western philosophy of religion for proving the existence of God.

The truth of existence, first of all, refer to its nature that is pure existence, which is not any thing other than richness, then to other limited existent beings, which are not any thing other than poor-ness (not a poor existent being). This is what Seddiqin argument wants to demonstrate.

Therefore, in the light of fundamental reality of existence not only we may obtain a deeper idea of God and his relation to the world and a valuable argument for proving His existence but also we may think of other philosophical subjects in a new and deeper meaning and demonstrations.