Ancient medical practitioners had conflicting views of the significance of the brain. In the fourth century B. C., Aristotle considered the brain to be a secondary organ that served as a cooling agent for the heart and a place in which spirit circulated freely. He designated the space in which all the spirits came together as the sensus communis -- the origins of our much more metaphorical term, "common sense." Aristotle had famously written, "There is nothing in the intellect that is not in the senses." As we can see, he meant this quite literally.