“But the birthday was a special occasion.  I might have abandoned my regular habits, on that night of all others.”

Betteredge considered for a moment.

“You did go out of your habits, sir,” he said.  “And I’ll tell you how.  You looked wretchedly ill—­and we persuaded you to have a drop of brandy and water to cheer you up a little.”

“I am not used to brandy and water.  It is quite possible——­”

“Wait a bit, Mr. Franklin.  I knew you were not used, too.  I poured you out half a wineglass-full of our fifty year old Cognac; and (more shame for me!) I drowned that noble liquor in nigh on a tumbler-full of cold water.  A child couldn’t have got drunk on it—­let alone a grown man!”

I knew I could depend on his memory, in a matter of this kind.  It was plainly impossible that I could have been intoxicated.  I passed on to the second question.

“Before I was sent abroad, Betteredge, you saw a great deal of me when I was a boy?  Now tell me plainly, do you remember anything strange of me, after I had gone to bed at night?  Did you ever discover me walking in my sleep?”

Betteredge stopped, looked at me for a moment, nodded his head, and walked on again.

“I see your drift now, Mr. Franklin!” he said “You’re trying to account for how you got the paint on your nightgown, without knowing it yourself.  It won’t do, sir.  You’re miles away still from getting at the truth.  Walk in your sleep?  You never did such a thing in your life!”

Here again, I felt that Betteredge must be right.  Neither at home nor abroad had my life ever been of the solitary sort.  If I had been a sleep-walker, there were hundreds on hundreds of people who must have discovered me, and who, in the interest of my own safety, would have warned me of the habit, and have taken precautions to restrain it.

Still, admitting all this, I clung—­with an obstinacy which was surely natural and excusable, under the circumstances—­to one or other of the only two explanations that I could see which accounted for the unendurable position in which I then stood.  Observing that I was not yet satisfied, Betteredge shrewdly adverted to certain later events in the history of the Moonstone; and scattered both my theories to the wind at once and for ever.

“Let’s try it another way, sir,” he said.  “Keep your own opinion, and see how far it will take you towards finding out the truth.  If we are to believe the nightgown—­which I don’t for one—­you not only smeared off the paint from the door, without knowing it, but you also took the Diamond without knowing it.  Is that right, so far?”

“Quite right.  Go on.”