Hence at any moment only part of the visual elements of a scene is available for conscious perception. - Michael S. Gazzaniga

Penfield wrote, “Consciousness continues, regardless of what area of cerebral cortex is removed. On the other hand consciousness is inevitably lost when the function of the higher brain stem (diencephalon*) is interrupted by injury, pressure, disease, or local epileptic discharge.” Yet he is quick to qualify that “to suggest that such a block of brain exists where consciousness is located, would be to call back Descartes and to offer him a substitute for the pineal gland as a seat for the soul.”6

W.J. was a warm, affable man, and the two hemispheres of his brain seemed to be working fine together, although they were no longer in direct communication. One of them talked, one of them didn’t. Given the way the brain is wired, that meant the left, talking brain viewed the visual world to the right of a fixated point and the right, non-talking hemisphere viewed all the visual information to the left of the same point. Given this surgical state, I wondered: If I flashed a light over to the right, would W.J. say he saw it? Light should go to the left hemisphere, and the left hemisphere had speech; it should be easy. It was, and W.J. easily declared he saw it. A bit later, I flashed the same light over to the left side of space and waited to see if he would say anything. He didn’t. I pressed him and asked if he had seen anything, and he firmly said “No.” Was he blind on that side? Or was that simple spot of light no longer communicated to the half brain that talked? Did the seemingly mute right brain know it had viewed a light? Was it conscious? What was going on?

Or really, the question is: Is there a difference between when life begins and when life as a human begins?