“But,” cried Leslie, who during this speech had found obvious difficulty in containing himself, “what is this instinct which you bid us follow?  What authority has it?  What validity?  What is its content?  What is it, anyhow, that it should be set up in this way above reason?”

“As to authority,” replied Parry, “the point about an instinct is, that its authority is unimpeachable.  It commands and we obey; there’s no question about it.”

“But there is question about the content of Good.”

“I should rather say that we make question.  But, after all, how small a part of our life is affected by our theories!  As a rule, we act simply and without reflection; and such action is the safest and most prosperous.”

“The safest and most prosperous!  But how do you know that?  What standard are you applying?  Where do you get it from?”

“From common sense.”

“And what is common sense?”

“Oh, a kind of instinct too!”

“A kind of instinct?  How many are there then?  And does every instinct require another to justify it, and so ad infinitum?”

“Logomachy, my dear Leslie!” cried Parry, with imperturbable good-humour.  He had a habit of treating Leslie as if he were a clever child.

“But really, Parry,” I interposed, “this is the critical point.  Is it your view that an instinct is its own sufficient justification, or does it require justification by something else?”

“No,” he said, “it justifies itself.  Take, for example, a strong instinct, like that of self-preservation.  How completely it stands above all criticism!  Not that it cannot be criticised in a kind of dilettante, abstract way; but in the moment of action the criticism simply disappears in face of the overwhelming fact it challenges.”

“Do you mean to say, then,” said Leslie, “that because this instinct is so strong therefore it is always good to follow it?”

“I should say so, generally speaking.”

“How is it, then, that you consider it disgraceful that a man should run away in battle?”

“Ah!” replied Parry, “that is a very interesting point!  There you get a superposition of the social upon the merely individual instinct.”

“And how does that come about?”

“That may be a matter of some dispute; but it has been ingeniously explained as follows.  We start with the primary instinct of self-preservation.  This means, at first, that each individual strives to preserve himself.  But as time goes on individuals discover that they can only preserve themselves by associating with others, and that they must defend society if they want to defend themselves.  They thus form a habit of defending society; and this habit becomes in time a second instinct, and an instinct so strong that it even overrides the primary one from which it was derived; till at last you get individuals sacrificing in defence of the community those very lives which they originally entered the community to preserve.”