Zen is quite OK in mentioning non-duality: it is the nearest to Advaita, but it is still inferior.+

Thoughts arise to the person within the waking or dream. The thinker is the form. Without the form, thinking is an impossibility. 

Thus, thinker and thoughts are part of the known. The witness of the knower and known is formless.

Thoughts and thinker have nothing to do with the formless witness. The witness is that witnesses the thoughts, thinker, and the world together and remains always within the waking or dream as their formless substance.

People think that the more they think, the more they will get; but it is really an error. It remains only a thought and gives them back only thoughts. Anything seen, or observed, cannot be the Self or the Witness.

Nondualistic awareness comes only when there is oneness in awareness in the midst of dualistic illusion or Maya. The dualistic illusion or Maya exists as a reality until the ignorance is there. Ignorance will vanish only when the non-dualistic or Advaitic wisdom dawns. 

The Advaitic wisdom dawns only when one becomes aware of the fact that the world in which you exist is a dualistic illusion or Maya created out of single stuff that is consciousness. 

Thus, by realizing that consciousness alone and all the three states are merely an illusion created out of consciousness leads to nondual Self-awareness.

Remember:~

Buddhist Sunyavada is incongruous because every thought has its opposite every word is tied to its coordinate for all thought and speech can only operate under such dualism. Hence, taking the most fundamental word, existence its implied opposite non-existence is also there, and vice versa. Therefore, the Sunya "non-entity" is meaningless without "entity". Both are there.

Buddhist Idealism speaks only of ideas.

What about the knower of these ideas?

Buddhist Nihilism does not ask "What is meant by Nihilism?

It is a thought.

 There must be a thinker of this thought.

Bhagavan Buddha kept silent, refusing to answer questions on the ultimate. Therefore, he was the wisest man in refusing to commit himself.

When you say "Nothing is" what is the meaning of "is"? "Sunya" is something that exists: you cannot prove that consciousness does not exist.

Remember:~

Zen is quite OK in mentioning non-duality: it is the nearest to Advaita, but it is still inferior because: ~

 (1) It fails to prove non-duality.

 (2) It illogically gives ‘Koan’ exercises as a means of attaining that which is beyond attainment, because always here.

 (3) It talks about insight or intuition to see Reality when sight involves a second thing, duality.

When you say "Nothing is" what is the meaning of "is"? "Sunya" is something that exists: you cannot prove that consciousness does not exist.

Zen Buddhism provides a highly important place for meditation practice. The truth is that Zen advocates the necessity of meditation for those of its adherents who cannot grasp the absolute truth.

Zen Buddhism is also on this lower stage of Yoga because it depends on flashes of Intuition gained by meditation, not by reasoning.

Has the Void a meaning? If so then it is only your imagination.

Remember:~

Bhagavan Buddha gave up yoga after practicing it for six years. He saw it could not yield truth.

Bhagavan Buddha gave up his austerities of yoga as impossible and useless. (Page.70/71 "Buddhism in Translation” by Warren)

Bhagavan Buddha got enlightenment only after he gave up Yoga. Unless you exercise your Buddhi--reason--there is no chance of getting the truth, which is beyond the form, time, and space. Buddhism is based on the form alone, and it does not include time and space in its investigation.

Buddhism has not proved the truth of Nonduality. Buddha pointed out the unreality of the world. He told people they were foolish to cling to it. But he stopped there. He came nearest to Advaita in speech but not to Advaita fully.

Zen Buddhism Satori is not Advaitic wisdom because it comes as flashes, it does not depend on seeing the world and does not depend upon mental sharpness so much as intuition.

Zen Buddhists are only mystics ~ they do not offer proof. How is their main method different from that of Christian mystics, and Hindu mystics, all of whom do not seek to prove by reason, but by "I know," intuition?: ~ Santthosh Kumaar