THE EVOLUTION OF THE BRAIN
an infinite variety of delicately adjusted actions in the service of the will, the eyes that see, the ears that hear, the hands that feel—these and scores of other complicated pieces of mechanism in the body are surely the mind’s instruments, such as in many other living creatures perform essentially the same functions that they serve in man. But almost every organ in the body plays a part in determining the appetites and desires, the feelings and the thoughts. In ancient times the Bible gave expression to the views then current among men and attributed such influences to “the reins and the heart” and to the bowels that were said “to yearn.” Modern science has revealed with greater precision the part each organ plays (by means of its nervous connections as well as by the “chemical messengers” or hormones it discharges into the blood stream) in stimulating the dominant appetites and affecting our feelings and emotions—in fact, in shaping our behaviour.
I have mentioned these conceptions merely to emphasize the fact that no one organ or part of the body can be regarded exclusively as the organ of the mind, seeing that each and all, in their several fashions, may serve as instruments in exciting or expressing human behaviour. But I want to direct particular attention to the organ that plays the dominant part in our mental life—the organ whereby we are made aware of the sensory experiences that we call sight, hearing, smell, taste, and touch and all the other varieties of sensation, as well as of the feelings, appetites, and sentiments. This organ, however, controls the complicated reactions that find expression in behaviour. I do not intend to discuss the nature of the relationship between the activities of the brain and the phenomena of mind; my purpose is to call attention only to certain well-recognised facts and to discuss their meaning. We know that damage
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