Manifested (perishable) is eightfold (7.4) and un-manifested (eternal) is the life element which is beyond senses but supports the manifested like a string in an ornament of pearls (7.7). Manifested is under the influence of delusions caused by the three gunas (7.25); and by polarities of longing and aversion (7.27) which can be crossed by seeking refuge in HIM.   

Science concludes that this entire universe (manifested) was formed from a single point and all we see around us is connected to that point which once held near infinite capacity. A similar analogy will hold for un-manifested as well where we are all connected to a single point (paramatma) of infinite capacity through an invisible wire/cable. Delusions are a kind of resistance which prevents us from getting fully connected to this source. Shraddha (7.21) is like conductivity which helps us connect ourselves to this powerful source that will help fulfil desires (7.22) as in the case of the four types of devotees (7.16). When one's shraddha is at a hundred percent, it's like superconductivity as Krishna says, "I consider them as My ownself' (7.18). 

Gita is experiential and the best way to experience this chapter is to analyse past life experiences where we were under the grip of delusions. Once we understand delusions, we become sakshi (witness) when we encounter delusions in the present moment without getting affected. This is the eternal state of ultimate freedom (moksha).