The thinker cannot think without the form, because the thought will not erupt without the form. Thus thinker is still a physical entity. Until he accepts the whole waking experience as 'I', he will not be able to unfold the mystery of the mind.
It is necessary to know 'I' is the whole Waking experience [mind or duality], not limited to physical body alone. If one remains stuck to the idea of 'I', to physical entity, he will remains stagnant within the mind [duality]. Therefore, it is necessary to know the nature of the mind which appears and disappears as experience of duality, to realize the fact that the truth is hidden in the mind as its invisible substance and witness.
Observing the thinker and the thought is not the means to overcome the duality. The thinker and the thought are with in the mind, therefore observing them, keeps the seeker within the scope of duality, not beyond.
