Chathurmurthy or Bhagavan in four forms

What is Vyashti and Samashti which is often translated as Mmicrocosm and Macrocosm?

A very good and simple example given  to understand these two terms is an individual tree and a huge forest of which this individual tree is a part. So if we consider a forest, each tree that constitutes the forest is called Vyashti and the huge forest comprising all the trees is Samashti

There is another example which is a little deeper. Imagine there are several water drops on a surface and sun is reflected in each one of them. Each reflection is Vyashti. Now imagine that all the water drops join to form a puddle and sun reflects in that also. This reflected sun in the puddle of water is the Samasthi which is actually an aggregate of all the reflections in the individual drops. There is no difference between these two reflections except one is aggregate. This definition helps us to understand that Sun remains the same independent of the reflecting surface. 

In both Samashti or Macrocosm  and Vyashti or Microcosm, Bhagavan  has four moorthis or forms. What are they?

In Samasthi, representing the gross (sthoola)manifested universe Bhagavan is Viraat Purushan filling all the Universe. Every entity, animate or inanimate, is a part of this Virat Purushan. 

Second form represents the subtle (sookshma) state called Sookshmaathman or Hiranyagarbhan

Third one represents the causal (kaarana) state called Avyaakruthan or Easwaran

Fourth form represents a state beyond all these called Thuriyan or Paramaathma.

Now take the Vyashti or Microcosm. In the waking state Bhagavan is present as Viswan.  When Jeevaathma identifies itself with the gross body then it is called Viswan

In the dream state,He is present and Thaijasan. In this state Jeevaathma identifies itself with the subtle body .

In the deep sleep state Bhgavan is present as Praanjan. Jeevaathma identifies with the causal or most subtle body and that is Praanjan

And in the state beyond these three states , He is called Thureeyan or Paramaathma. When Jeevaathma identifies with Paramaathma, it becomes Paramaathma.

Bhagavan is also known as Chathurmurthy because He exists in the above four  forms in each Vyashti and Samashti 

May Chaturmurthy bless us in all the three states of Jaagrath, swapna and sushupthi and lead us to the fourth to be one with HIm!