Around 300 BCE, a Chinese philosopher named Zhuangzi woke from a dream and sat very still. He had dreamt he was a butterfly - fluttering, weightless, completely unaware of being a man. The dream was so vivid that when he opened his eyes, he genuinely wasn't sure: Was he a man who had dreamed of being a butterfly, or a butterfly now dreaming of being a man? He never fully answered it. For most of human history, that's where consciousness lived - in philosophy, in the quietly unsettling feeling that something is happening inside you that no one else can ever reach. Aristotle thought it was in the heart. Descartes declared "I think, therefore I am" - beautiful, but scientifically, it tells us almost nothing. Here is the question science has been wrestling with for four decades: Is consciousness something your brain generates - an internal product of neurons and electricity - or is it something the brain simply receives? Like a radio picking up a signal already out ther...