Only I can’t use the memory, for I don’t know that I’ve got it, and can’t call it into being when I wish. But every now and then something happens to turn on the tap of the subconscious, and a thin trickle comes through. I find myself sometimes remembering names I was never aware of having heard, and little incidents and details I had never consciously noticed. Imagination, you will say; but it isn’t, for everything that that inner memory provides is exactly true. I’ve tested it. If I could only find some way of tapping it at will, I should be an uncommonly efficient fellow. Incidentally I should become the first scientist of the age, for the trouble with investigation and experiment is that the ordinary brain does not observe sufficiently keenly or remember the data sufficiently accurately.”

“That’s interesting,” I said. “I’m not at all certain I haven’t noticed the same thing in myself. But what has that to do with the madness that you say is infecting the world?”

“Simply this. The barriers between the conscious and the subconscious have always been pretty stiff in the average man. But now with the general loosening of screws they are growing shaky and the two worlds are getting mixed. It is like two separate tanks of fluid, where the containing wall has worn into holes, and one is percolating into the other. The result is confusion, and, if the fluids are of a certain character, explosions. That is why I say that you can’t any longer take the clear psychology of most civilised human beings for granted. Something is welling up from primeval deeps to muddy it.”

“I don’t object to that,” I said. “We’ve overdone civilisation, and personally I’m all for a little barbarism. I want a simpler world.”

“Then you won’t get it,” said Greenslade. He had become very serious now, and was looking towards Mary as he talked. “The civilised is far simpler than the primeval. All history has been an effort to make definitions, clear rules of thought, clear rules of conduct, solid sanctions, by which we can conduct our life. These are the work of the conscious self. The subconscious is an elementary and lawless thing. If it intrudes on life two results must follow. There will be a weakening of the power of reasoning, which after all is the thing that brings men nearest to the Almighty. And there will be a failure of nerve.”

I got up to get a light, for I was beginning to feel depressed by the doctor’s diagnosis of our times. I don’t know whether he was altogether serious, for he presently started on fishing, which was one of his many hobbies. There was very fair dry-fly fishing to be had in our little river, but I had taken a deer-forest with Archie Roylance for the season, and Greenslade was coming up with me to try his hand at salmon. There had been no sea-trout the year before in the West Highlands, and we fell to discussing the cause. He was ready with a dozen theories, and we forgot about the psychology of mankind in investigating the uncanny psychology of fish. After that Mary sang to us, for I considered any evening a failure without that, and at half-past ten the doctor got into his old ulster and departed.

As I smoked my last pipe I found my thoughts going over Greenslade’s talk.