We feel like more than just the sum of a trillion neurons. We feel like more than just three pounds of wet flesh, and so simply describing the brain in terms of its neurotransmitters and neurons and all these chemicals and exciting ingredients doesn't fully grapple with what it feels like to be human, the first person subjective experience of being a conscious being. When you think about the really grand epic questions of neuroscience ... what is consciousness? How can we form a scientific explanation for consciousness, for human experience? That is the holy grail.