Is Consciousness Produced by the Brain, or Is the Brain Inside Consciousness?
Schrodinger declared consciousness is not plural. The Mandukya said it first.
David Chalmers names the hard problem of consciousness in Tucson, 1994. Erwin Schrödinger had already answered it in Vienna, reading Paul Deussen's German Upaniṣads. The Māṇḍūkya stated the answer in twelve Sanskrit verses 2,500 years earlier, with turīya, the silent fourth, at the centre.
At the Arizona Conference
April 1994. In a hotel ballroom in Tucson, Arizona, a twenty-seven-year-old Australian philosopher named David Chalmers steps up to give a talk at a conference called 'Toward a Scientific Basis for Consciousness'. He is not yet famous. He is about to become so, for the next forty years of his career, because of the distinction he is about to draw.

There are problems about consciousness that science can solve, Chalmers says. How the brain discriminates colours. How it focuses attention. How it integrates information. How it produces behaviour. These are difficult but tractable. Give neuroscience enough time and it will get them. Chalmers calls these the easy problems.
Then there is one more. Why is any of this accompanied by a felt interior? Why is there something it is like to see red, rather than merely a mechanism that processes wavelengths? A full neuron-by-neuron description of a human being could be given without ever explaining why that description has a subject inside it, a someone reading the description from within. There is an explanatory gap, and the gap is not one that science is going to close with more grant money. It is a gap of a different kind.
Chalmers calls this the hard problem of consciousness. The name sticks. Within a year he publishes Facing Up to the Problem of Consciousness, and the year after that his book The Conscious Mind. The entire philosophy of mind reorganises around the distinction. Almost every contemporary philosopher of mind now has to take a position for or against Chalmers's framing.
What almost nobody in the Tucson ballroom knew that day is that the question already had a name. It had a systematic treatment, in twelve Sanskrit verses, composed somewhere between 500 and 200 BCE. The text was called the Māṇḍūkya Upaniṣad, short enough to be memorised in a single afternoon. A Nobel-winning physicist in Vienna had already read it carefully decades earlier and said, in print, that it was the only metaphysical framework he had ever found that could hold quantum mechanics without contradiction. His name was Erwin Schrödinger, and his sentence was this: consciousness is a singular of which the plural is unknown. What follows is how the Upaniṣad, Schrödinger, and Chalmers, across twenty-five centuries, end up pointing at the same thing, and where the Upaniṣad goes further than either of them.