Upadhis

Because they are not mutually contradictory action can not eliminate ignorance. Only knowledge destroys ignorance just as darkness is dispelled by light. 
                                                                                                Atma Bodha" Sankaracharya 

We have been discussing a lot about Atma and anatma. Atma is the real subject while the anatma is any object other than the subject. We have tried to establish that the ego is not a subject at all or only anatma. It is nothing but an imaginary construct. So we had said there is no doer or experiencer  in reality. It is good to understand why this happens. The real self is hidden by a superposition of anatma.
We can understand this as follows. If something is hidden by something else then there are two effects of this process. The hidden thing is never experienced . Secondly whatever is hiding it becomes or transfers some attributes to the hidden thing. The body-mind hides the atma and thereby making it unknown. Secondly the mind or a vritti in it becomes or assumes the place of the atma or the subject.Whatever hides something else and creates a false sense of the hidden thing is called a upadhi. The body and mind through their sensory perceptions and thought processes create the upadhi on the atma. In short because of this covering effect, the upadhis seems to us like the real self or atma.
How can we understand a upadhi?. There are three things that should happen.
1) The upadhi hides the real thing
2) The upadhi assumes the identity of the real thing by transferring its attributes.
3) The upadhi is always a false superposition.

Let us understand this with an example. If we take a crystal which is white and keep it near a flower which is red, we can see a red hinge on the crystal. Now we can say the flower is an upadhi as it transfers its attributes namely color to the crystal which is colorless. This superposition is false as the crystal is not actually red. If we remove the flower the crystal always remains white. So the white color or purity of the crystal is hidden by the flower. The transfer of color is false as it is only a temporary superposition.
If we sit on a dirty floor , the mud can get into your dress. The dirtiness of the floor has been transferred to your dress. However this transfer is real . As you have to clean your dress to remove the color. So karma is required to remove the dirt. Thus it doesn't satisfy the third aspect of upadhi. So dirt is not an upadhi, while the flower is a upadhi because the color is not actually transferred it is only a visual effect.
So the power of upadhi is to veil the reality and impose upon it a false reality. This is called adhyasa. The illusion created out of adhyasa are called avarana shakti and vikshepa shakti.
In common day parlance we can see this in many levels. The gross body's attributes are superimposed on the subject. Thus i would say "I am fat" or "I am thin". The body's attributes are now superimposed on the pure subject.We now know that the pure subject is neither fat nor thin and it has no attributes at all. The same applies to the statement "I am worried" or " I am happy". The state of the mind is transferred to the subject.
If you look at the dream state and deep sleep state , again the same superposition works. In the dream the dream subject replaces our atman and we feel miserable or happy based on that . On waking we feel that this was a false superposition. Similarly the deep sleep state of bliss is also a false superposition on the atma.
So the upadhis here are body and mind which silently superimpose the attributes and creates the false impression on the subject. The idea of spiritual life is to see this adhyasa and turn away from it just like removing the flower and seeing the purity of the crystal. As we saw in the case of the crystal, the superposition is only an illusion not a real one when compared to the to  the case of the dirt on the dress. The antidote to this false superposition in right knowledge and not any sadhana or effort. Sadhana or karma are all preparation to this knowledge. As Sankaracharya tells us in "Atma Bodha", the only means of liberation is atma jyana and there exists no other solution.