“I thought you might be,” said the specialist, drily. “Well, now. You know quite well that the strain you put on your nerves during the war has left its mark on you. It has left what I may call old wounds in your brain. Sensations received by your nerve-endings sent messages to your brain, and produced minute physical changes there—changes we are only beginning to be able to detect, even with our most delicate instruments. These changes in their turn set up sensations; or I should say, more accurately, that sensations are the names we give to these changes of tissue when we perceive them: we call them horror, fear, sense of responsibility and so on.”
“Yes, I follow you.”
“Very well. Now, if you stimulate those damaged places in your brain again, you run the risk of opening up the old wounds. I mean, that if you get nerve-sensations of any kind producing the reactions which we call horror, fear, and sense of responsibility, they may go on to make disturbance right along the old channel, and produce in their turn physical changes which you will call by the names you were accustomed to associate with them—dread of German mines, responsibility for the lives of your men, strained attention and the inability to distinguish small sounds through the overpowering noise of guns.”
“I see.”
“This effect would be increased by extraneous circumstances producing other familiar physical sensations—night, cold or the rattling of heavy traffic, for instance.”
“Yes.”
“Yes. The old wounds are nearly healed, but not quite. The ordinary exercise of your mental faculties has no bad effect. It is only when you excite the injured part of your brain.”
“Yes, I see.”
“Yes. You must avoid these occasions. You must learn to be irresponsible, Lord Peter.”
“My friends say I’m only too irresponsible already.”