In a review by Steven Poole of Edelman and Tononi’s Consciousness: How Matter Becomes Imagination I found this:

…they claim that Schopenhauer called the problem of consciousness the “world knot”, and adopt this lovely image as their catchphrase. But that is not what Schopenhauer said. What he calls the “world knot”, in On the Fourfold Root of the Principle of Sufficient Reason, is “the identity of the subject of willing with that of knowing”. Edelman and Tononi give a remarkably rich and provocative hypothesis of the subject of knowing, but the will soars free, as yet untethered by physical explanation.

Great image – very norse – and the identity of the subject of will with the subject of knowing is definitely a biggie, both for the psychology and metaphysics of consciousness.