We next come to psychology. I am looking at you. The external sensations are brought to me by the eyes; they are carried by the sensory nerves to the brain. The eyes are not the organs of vision. They are but the external instruments, because if the real organ behind, that which carries the sensation to the brain, is destroyed, I may have twenty eyes, yet I cannot see you. The picture on the retina may be as complete as possible, yet I shall not see you. Therefore, the organ is different from its instruments; behind the instruments, the eyes, there must be the organ So it is with all the sensations. The nose is not the sense of smell; it is but the instrument, and behind it is the organ. With every sense we have, there is first the external instrument in the physical body; behind that in the same physical body, there is the organ; yet these are not sufficient. Suppose I am talking to you, and you are listening to me with close attention. Something happens, say, a bell rings; you will not, perhaps, hear the bell ring. The pulsations of that sound came to your ear, struck the tympanum, the impression was carried by the nerve into the brain; if the whole process was complete up to carrying the impulse to the brain, why did you not hear? Something else was wanting — the mind was not attached to the organ.