Recall the original strange mantra we started with.
“That is complete. This (too) is complete. (This) complete has come from (that) complete. When complete is removed from complete, what remains is also complete”
If we equate ‘that’ to the original ‘That’ which alone existed in the beginning (recall the Chändogya Upanishad creation story) and ‘this’ to our perceptible world we see around, including us, the meaning of this apparently strange mantra becomes almost clear.
This world came from ‘That’. And as per the Upanishad, even after this world came out, ‘That’ remained as it was. ‘That’ did not get transformed into ‘this’. It took more forms and coexists with all those forms.
There is no doubt about the fact that the original ‘That’ was limitless or ‘complete’. But each of the forms taken by ‘That’ is definitely not limitless and complete. Each has its own shortcomings.
If that is the case, how does the above mantra say that ‘this’ is also complete?
We probably have to see each of the entities in ‘this’ sans the name and form it has taken. What do we see there? ‘this’ is same as ‘That’. This is what exactly, many Upanishads say – when all names and forms are dropped, ‘this’ becomes indistinguishable from ‘that’ or in some way ‘this’ merges with ‘That’ in the same way “the rivers merge with the sea when they finally lose their individual names and forms”. Before merging, each river had a name and its own characteristics such as speed, breadth, length, force and so on. But once they merge with the sea, there is no river but just the sea.
This is also the momentary experience one gets in advanced stages of meditation or samädhi. When the identity with the body is overcome, the limited ‘I’ becomes universal ‘I” which is limitless.
So, ‘this’ is also ‘complete’ in reality.
PS: I am aware of possible objections some staunch Dvaita adherents may have to my explanation. I am only trying to unify diversity in views and see sense in various Upanishadic verses, and great philosophies of these masters whom I hold in high esteem. After all, in the domain of ‘infinity’ our ‘limited’ algebra does not work as we saw earlier.