One can only know an experience when one discriminates between it and the state of mind when it was nonexistent just as he knows a black by its contrast to white.

Waking or dream is only a seen(object), no matter how exalted it be. Waking or dream never touches the formless witness, but formless witness remains always in the seen as its formless substance. It is erroneous to believe that the more one thinks, the more he will get. The thought remains as a thought and gives you back only a thought not truth. One has become aware of the fact the thoughts arise only within the waking or dream. Thus one has to trace the source of the three states not the source of the thought to unfold the mystery of the duality. 

One can only know an experience when one discriminates between it and the state of mind when it was nonexistent just as he knows a black by its contrast to white. 

The only certain thing about the waking is that it is forever changing; it changes in deep sleep and deep sleep changes into the dream, no one can prevent this change it is happening on its own accord. In contrast to the three states, the soul or witness of the three states is the only thing of whose unchanging character one can be certain. Through the soul or witness one becomes aware about all the changes in consciousness, remaining itself relatively constant, as a standard of reference for them. 

The term witness, Seer, Self is used in a non-dual sense, without reference to the three states witnessed, absolute awareness, not relative. –FORMLESS PATH