It has not been possible to preach Advaitic Truth entirely free from the settings of dualistic weakness.+

Many people think Sage Sankara's path is the path of Advaitic orthodoxy is substantially not true. Some philosophers in the world are as misunderstood and misinterpreted.

Most of the harm came from his orthodox followers. The ideas that Sage Sankara rejected came back to the Advaita fold and, the wisdom–oriented teachings of Sage  Sankara became as much a face of Advaita as the rituals, worships, and other practices.

Sage  Sankara treated ignorance as an error, the removal of which led to wisdom He left it at that. His followers, however, wrote tomes speculating the causes for ignorance, nature of ignorance, different forms of ignorance, etc. had the Guru watched his disciples at work he might have wondered whether they were studying about Brahman or about ignorance.

Brahman— The One Without A Second 

The Atman is self-evident (Svatah-Siddha). It is not established by extraneous proof. It is not possible to deny the Atman because It is the very essence of the one who denies It. The Atman is the basis of all kinds of knowledge, presuppositions, and proofs. Self is within, Self is without; Self is before, Self is behind; Self is on the right, Self is on the left; Self is above and Self is below. Brahman is not an object, as it is Adrisya, beyond the reach of the eyes. Hence the Upanishads declare: “Neti Neti—not this, not this....” This does not mean that Brahman is a negative concept, or a metaphysical abstraction, or a nonentity, or a void. It is not another. It is all-full, infinite, changeless, self-existent, self-delight, Self-knowledge, and self-bliss. It is Svarupa, essence. It is the essence of the witness. It is the Seer (Drashta), Transcendent (Turiya), and Silent Witness (Sakshi).

Sage Sankara’s Supreme Brahman is impersonal, Nirguna (without Gunas or attributes), Nirakara (formless), Nirvisesha (without special characteristics), immutable, eternal, and Akarta (non-agent). It is above all needs and desires. It is always the Witnessing Subject. It can never become an object as it is beyond the reach of the senses. Brahman is non-dual, one without a second. It has no other besides it. It is destitute of difference, either external or internal. Brahman cannot be described because the description implies a distinction. Brahman cannot be distinguished from any other than It. In Brahman, there is not distinction between substance and attribute. Sat-Chit-Ananda constitutes the very essence or Svarupa of Brahman and not just Its attributes. The Nirguna Brahman of Sage Sankara is impersonal.

From the standpoint of the formless Soul, the Self, the effect is non-different from the cause. However, in the realm of duality cause is different from effect. The non-difference of the effect from the cause has to be grasped perfectly to realize from the ultimate standpoint there is neither the cause nor the effect because the cause and effect are one in essence. That essence is consciousness.

Sage Sankara says: ~  If the cause is destroyed, the effect will no longer exist. For example, if from the effect, cotton cloth, the cause, threads, are removed, there will be no cloth, i.e., the cloth is destroyed. Similarly if in the effect, thread, the cause, cotton, is removed, there will be no thread, i.e., the thread is destroyed. (Brahmasūtra Bhashya, commentary on the Brahma-sutra, ^[9] 2.1.9)

Despite the non-difference between cause and effect, the effect has itself in the cause but not the cause in the effect. The effect is the nature of the cause and not the cause, the nature of the effect. Therefore the qualities of the effect cannot touch the cause because the cause and effect are present only when the duality is present. 

The duality is present only when there is an illusion. The illusion is there only when there is ignorance. When there is no ignorance then there is no illusion. When there is no illusion then there is no duality. When there is no duality then there is no cause and effect. When there is no cause and effect then there is the nondual reality.    

Sage Sankara says: - During the time of its existence, one can easily grasp that the effect is not different from the cause. However that the cause is different from the effect is not readily understood. As to this, it is not really possible to separate cause from effect. But this is possible by imagining so. For example, the reflection of the gold ornament seen in the mirror is only the form of the ornament but is not the ornament itself as it (the reflection) has no gold in it at all. (Chāṃdogya Upaniṣad Bhāṣya, commentary on the Chandogya Upanishad, 6.3.2)

All names and forms are real when seen with the Sat (Brahman) but are false when seen independently of Brahman.

This way the seeker of truth establishes the non-difference of effect from cause.

In the context of Advaita Vedanta:~Jagat (the world) is not different from Brahman; however, Brahman is different from Jagat

It has not been possible to preach Advaitic Truth entirely free from the settings of dualistic weakness it has not been more operative and useful to mankind at large because only a few will be able to grasp and realize it.

'To realize the Advaitic Truth a freer and fuller scope the seeker has to realize the form, time and space are one in essence. And that essence is consciousness. And the Soul, the Self is present in the form of consciousness.   

To realize the Advaitic truth the seeker has to be free from all superstitions and orthodox contaminations. The seeker has to be dedicated to acquiring Self-knowledge or Brahma Gnana or Atma Gnana   alone.'

A  Gnani will easily appreciate the high flights of Sage Sankara’s Advaitic wisdom is one of the 'most majestic structures and valuable products of the Genius of man in his search for Truth. :~Santthosh Kumaar