The Ultimate Reality or Truth cannot be known. So what could be the purpose of any body of knowledge, including Vedanta?
Truth cannot be known but it can be lived. In fact we are, and have always been, living that truth, says Vedanta. That is what is meant by the declaration “Thou Art That”. We live because of that Truth. But, because of ignorance (avidya) we are not aware of it, considering ourselves to be this changing, perishable body-mind-intellect. Ignorance covers the Truth, the Existence-Consciousness-Bliss.
The purpose of Vedanta or any spiritual knowledge is to only get rid of this ignorance. It “burns” ignorance in “jñānāgni” or “fire of knowledge”. Vedanta does not instruct us directly on “What is” but educates us on what is not true. Once ignorance covering the Truth is completely removed the self-luminous Reality reveals itself jut as the ever-shining sun is revealed when its cloud cover is blown away. This unique approach of Vedanta to Reality is famously known as the “neti, neti” (“not this, not this”) logic of reasoning.
Ultimate Reality seems to be totally out of the focus of traditional science with its emphasis on knowing “what is” about the seen world.