The Eastern heart and Galen's ventricle: a historical review of the purpose of the brain.

The seat of consciousness has not always been thought to reside in the brain. Its "source" is as varied as the cultures of those who have sought it. At present, although most may agree that the central nervous system is held to be the root of individualism in much of Western philosophy, this has not always been the case, and this viewpoint is certainly not unanimously accepted across all cultures today. In this paper the authors undertook a literary review of ancient texts of both Eastern and Western societies as well as modern writings on the organic counterpart to the soul. The authors have studied both ancient Greek and Roman material as well as Islamic and Eastern philosophy. Several specific aspects of the human body have often been proposed as the seat of consciousness, not only in medical texts, but also within historical documents, poetry, legal proceedings, and religious literature. Among the most prominently proposed have been the heart and breath, favoring a cardiopulmonary seat of individualism. This understanding was by no means stagnant, but evolved over time, as did the role of the brain in the definition of what it means to be human. Even in the 21st century, no clear consensus exists between or within communities, scientific or otherwise, on the brain's capacity for making us who we are. Perhaps, by its nature, our consciousness--and our awareness of our surroundings and ourselves--is a function of what surrounds us, and must therefore change as the world changes and as we change.