Because one sees the world –he thinks he is a person and starts figuring how to mange his life in the world, thus it makes him think he is an individual, and he is separate from the world. But he is unaware of the fact that he and the world exists only within the waking experience. Therefore it is necessary for the seeker to realize the fact the he and his world are within the waking experience [mind or `I']
Thought, ego experience, duality appears and disappears together along with the waking experience. Absent of waking experience present of Ataman in its formless nondual nature. Thus dual [waking and dream] nondual [deep sleep] is nature of Ataman. If Ataman in illusion [duality] it is called mind or `I'. If mind is in its formless nondual nature it is called Ataman.
The Waking experience or dream as a whole is visible only to the formless witness [Ataman]. The waking experience or dream is an object to the Ataman [formless witness]. This has to be grasped. Then only it is possible to move a head in the pursuit of truth.
