Why does processing information feel like something at all?

Philosopher David Chalmers separated the 'easy problems' of consciousness — explaining how the brain discriminates, integrates and reports information — from the 'hard problem': why any of that physical processing is accompanied by subjective experience at all. Even a complete map of the brain's wiring wouldn't obviously explain why there's something it's like to see red.

— David Chalmers, Facing Up to the Problem of Consciousness — Journal of Consciousness Studies, 1995