Now your questin:'what are you when you are not thinking?'
You deed not stated as your premisse: Cogito ergo sum.
To make you question managable for my way of,uh, seeing
I must rephrase your question. Say: in what state is your
brain when you are not thinking?
Well I assume that this is the case when I and my brain are
sleeping.There may be some dreaming activity but I dare not
to mention Freud and his Traumdeutung.
The assumption is incorrect.
Consciousness has nothing to do with thought; as soon as you achieve a state of consciousness without thought, it can be said that you are super-conscious: Present, in the now, in a state of Being. The idea of thought being the Being is incorrect- it comes out of the mind trying to convince you that it is you. It is not- it is a tool for you.
This is the difference between philosophy and knowledge. 'Cognito ergo sum' is philosophy, a statement to explain behavior, misleading.. certainly not real. Knowing that your consciousness exists in a state of true Being when thought is silenced is actual knowledge.