I’m going to write about the development of the idea of superimposition (adhyasa) and mutual superimposition in the preamble to the commentary by Adi Sankaracarya on the Brahma Sutra Bhasya. It starts off with the classic aporia: how does that out there the object, material and limited come to be in here in my consciousness which is immaterial and therefore unextended as such. To develop the theory that he proposes he offers the analogy of confusion ie. a rope coming to be seen as a snake. The snake is superimposed on our consciousness. To use the example of confusion as an example of what happens during normal veridical perception is to say the least paradoxical and asking for trouble. Anyway that is the first adhyasa example, two ‘external’ objects are confused. I have ‘external’ in quotes to remind you that Sankara is a realistic thinker and that there is no truck with the contrast between ‘external’ and ‘internal’.
Moving on from that there is the development of what I am going to call the second adhyasa, the ‘internal’ one in which the qualities of the mental and physical are superimposed on the self and the nature of the self is superimposed on the physical and mental. This is objected as not being a true superimposition which involves two external objects. If it were really superimposition in the first sense the self and the mind/body/ would cancel each other out. The dialogue between the Master and the Disciple in Sankara’s ‘Upadesa Sahasri’ Chap.2: #54/#55 develops this debate.
My analysis of what must have been a common impasse in the acceptance of the teaching is that the second/mutual superimposition analogy is developed on the basis of the first which is a natural phenomenon and therefore germane to standard perception whilst the second is to do with a spiritual and simultaneous event, the classic form of avidya/ignorance. In the first adhyasa the items supplant each other, in the second adhyasa there is interpenetration. It’s like the famous cartoon of the duck/rabbit. Which is it, both or neither?
“The teacher said: “Listen. It is true that the Self and the body are well-known, but they are not well-known to all people to be the objects of different knowledges, like a human being and a trunk of a tree. (Question: How are they known then?) (Reply) (They are always known) to be the objects of an undifferentiated knowledge. For no one knows them to be the objects of different knowledges saying, ‘This is the body’ and ‘This is the Self’. It is for this reason that people are deluded about the nature of the Self and of the non-Self and say, ‘The Self is of this nature’ and ‘It is not of this nature’. It was this peculiarity with reference to which I said that there was no such rule (viz. only well-known things could be superimposed on each other.)” (Ch.2:#54 ‘Upadesa Sahasri’.)
The focus of the first adhyasa is on the real transfer that occurs between the object and the mind of the pereceiver, that of the second adhyasa is on the unreal transfer between the Self and the body.
I suppose what I’m trying to express is that when you move from the normal conventional reality of the First Adhyasa you move into the apophatic reality of the Second Adhyasa where language cannot go and knowledge is impossible because there is no other.

