शङ्कराचार्य Sankaracarya expounds the philosophy of अद्वैत advaita, non-duality, Duality, the differences and divisions is what we experience. Therefore the realm of diversity in which we live is not questioned by us. The upanisads explain that this perceived diversity is alright but it is not the ultimate reality. In the womb, in the core of this diversity is unity, oneness. There is a connecting link in all the disparity of the universe. There is a substratum that connects, supports and enlivens everything. There is one principle that sustains everything. That is सत्चितानन्द sat-cit-ananda – sat, existence; cit, awareness or intelligence; and ananda, wholeness or fullness.
We find that every object exists, manifests itself in awareness, has a purpose to serve and is the potential source of happiness. This is possible because it is sustained by the basic principle of sat-cit-ananda. Whatever there is in the universe is the manifestation of this principle. This is the teaching of the upanisads and this is what Sankaracarya brought to light. This is the teaching that can remove all the differences, divisions, animosities and enmities. Because we do not question the reality of what we perceive, the superficial diversities are given importance taking them to be the realities. This brings about conflicts. These conflicts can be resolved by recognizing that in the foundation of diversity, there is unity. At a certain level you and I are different but at the level of reality there is no difference regardless of who V we are or what it is. The good and the bad, the sentient and the insentient all are connected and informed by one reality.
Sankaracarya’s main teaching is that ignorance and misconception about the reality is the cause of sadness and suffering. All physical and mental suffering can be traced to ignorance. Therefore knowledge, true understanding is the solution to all the problems of humans.
Among all the schools of thought that developed in India, advaita-vedanta is most accepted by intellectuals. It is very much in keeping with the discoveries of science. Science also points to the oneness that is behind duality. It is said that matter is nothing but vibrations of energy. All the diversity in matter ultimately springs from one fundamental principle called energy. That means scientists are telling us about unity in diversity, which means diversity is unreal, मिथ्या mithya. The universe that we perceive is relative. As Einstein explained, the three dimensions that we perceive are not the whole reality. Suppose we were able to see only two dimensions, that is, we only could see the shadows of people on a wall. Then we would not know the person completely because we do not perceive the depth. Just as the two dimensions that shadows represent is a projection of a three dimensional person, so also the three dimensions that we perceive in the universe, is a projection of a higher reality.
What Sankaracarya taught as the vision of the upanisads is being verified by the discoveries of science as well. Vedanta is not a product of reasoning but it is not opposed to reasoning. That alone is truth which is no doubt independent, but at the same time, truth must be in keeping with reasoning.