Sacks never said that he was able to unlock the mystery of consciousness. The only thing he said in that essay (and elsewhere) is that we have no reason to assume that something super-natural is going on to account for hallucinations, even if they result in intense “transcendent” experiences.

Sacks isn’t denying NDE experiences. He’s saying there’s no evidence that something super-natural accounts for them.

Why are you bringing up love? Correct me if I’m mistaken, but your insinuation seems to be that this intense feeling of bonding closely with another person is somehow rooted in something that has nothing to do with human bodies.

“I don’t know” is my standard answer for anything you bring up that science can’t explain (yet). What caused the Big Bang? I don’t know. How did life begin on Earth? I don’t know. How did consciousness emerge in the world (which includes other animals besides us, of course). I don’t know.