The following was posted to the Advaitin Egroup in August 2008.
The tree in the yard is really in the yard and not in my head. What does this 'not in my head mean'? More importantly what does Advaita have to say about these issues?
The phrase 'not in my head' can be read to mean that the physical tree is not in my head which, on the face of it, is undeniable. Information about the tree is in my head in the form of sensory data or, if that is claiming too much, we can allow that there are cerebral events, neuronal activity and the like which are the sensorial impact of the tree in the yard.
Some authors have claimed that this is all that the tree amounts to and that the substantive tree is an inference from the data. This may be based on a theory about objects, which construes them as the union of substantive and attributes or matter and qualities etc. The jargon differs but the thinking is the same. Berkeley refutes this notion definitively by asking in effect, 'well if we never see this matter or substantive and cannot know it directly how do we come to be talking about it? Let us therefore cease to talk about matter, as it is purely a speculation which has no foundation'. Thus his thinking has come to be called immaterialism.
Advaita takes the view that the reality of the tree is present to the perceiver or that we perceive it and not our perceptions as Shankara put it. The tree can be present to us in its reality as an object because the understanding of what an object is differs radically from the substantive/attributes or matter/qualities conjecture. What makes an object capable of being perceived is its nature as an upadhi of pure consciousness. This is its true nature or the truth of its substratum.
It is this substratum which unifies the consciousness of the subject with the object. Remember that the brain is also an object which has also got pure consciousness as its truth or the reality of its substratum. The intellectual apprehension of the tree or the judgement, 'this is a tree before me', is of course different from the actual tree.
‘Therefore an object and its knowledge differ’ (B.S.B. II.ii.28).
In short we do not perceive the substratum but it is what makes perception possible. We can distinguish between the intellectual apprehension, the cerebral events and the tree but the substratum of all these is one and the same. It is in this ultimate sense that the object is before our minds.