Consciousness: a brief review of the riddle.

From the Department of Anesthesiology and Pain Management, Baylor University Medical Center, Dallas, Texas. Corresponding author: Peter T. Walling, MD, Department of Anesthesiology and Pain Management, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, Texas 75246. As I look at the full moon on a clear night, light travels between the moon and me in just over 1 second, enters my eyes and is focused on my retina, stimulating the photoreceptors, and . . . stops! That is as far as the moonlight goes. From here on, information about the moon travels the optic pathways of cranial nerves and brain—3 pounds in weight, 2 billion neurons, and upwards of 500 trillion synapses. Silently and in total darkness, a visual image is produced and projected back into space to clothe the object of my gaze so that it seems that the light shines directly from the moon into my mind’s eye. This illusion is so exquisite that I hardly recognize it as such. The moon now exists in my visual consciousness. But where is this awareness and where am “I”? More important, am “I” an observer of this occurrence or an integral part of it? Dualists claim mind and brain to be separate while materialists argue that the mind is the brain and that man has no immaterial part. Dualists and materialists have been dueling for centuries. At the present time, materialists seem to have the upper hand, but the fight is far from finished and the final answer may turn out to be a surprise for everyone.