To explain consciousness we must explain not just sensations but how a three-dimensional world is perceived without relying on an inner eye that can make sense of depth cues etc. because if the brain constructs a 3D model of the world, who or what perceives the model? Both problems are tackled in the book, as well as aesthetics and morality.
For instance, one argument, the argument from energy, goes like this:
Consciousness is real. It exists at least for me when I assert that it exists. It is thus, at the very least, at those times, a thing in the universe.
Consciousness comes and goes. There must be a change in some other aspect of the universe that makes at least the first of these transitions happen. Any change that induces either transition must involve energy of some kind (although if consciousness is an emergent property more elaboration is required).
Furthermore, whatever causal role we may ascribe to it, consciousness interacts with the physical world, at the very least to the extent that the brain governs the content of experience.
We take the physical world to be made up of fundamental particles (quarks, electrons, and so on). The candidates for the mechanism whereby consciousness comes about are such as: special arrangements of physical particles and changes in those arrangements (including e.g. emergence), OR transitions in the states and energy levels of those particles, OR interactions between particles of different kinds. Interactions, transitions, or establishing particular arrangements, as well as receiving content from the brain, all involve energy (although emergence demands more elaboration). Even the collapse of a wave function in quantum entanglement involves the energy of the interaction that triggers the collapse.
Since consciousness comes about through an energetic transaction, it must at least for some time appropriate some part of that energy for itself (i.e. the energy from the interaction, process or whatever that brings it about).
While energy is transmuted to underpin consciousness it is its own distinct form of energy (available to interact with like-energies in some characteristic way).
In this way, gradually and systematically, a full picture of the conscious mind is built up.
