ere right, after all, Potswood, and I was a fool to disregard your
warnings. I oughtn't to have dabbled--I should have left those things
alone.'

"I said nothing, thinking it best not to disturb him, but to leave him
free to say what he wanted to say in his own way. He remained quiet for
a minute or two more, and then sat up with an appearance of much greater
composure. 'You mustn't mind me, Potswood,' he said. 'As I've told you,
I'm in a bad state of nerves, and at best I'm an impulsive sort of
person, as you know. I needn't have bothered you like this--I came
rushing round here without thinking, and if the house had been a bit
farther off I should have come to my senses before I reached you. After
all, there's nothing so much to disturb one's-self about, and this
man--this Denson--may very well have deserved his fate. Don't you think
that likely?'

"He added this last question with an involuntary eagerness that scarcely
accorded with the indifferent tone with which he had begun. I answered
guardedly. I said of course nobody could say what the unhappy man's sins
might have been, but that whatever they were they could never justify
the fearful sin of murder. 'And,' I added, 'if you know anything of the
matter, Mason, or have the smallest suspicion as to who is the guilty
person, I'm sure you won't hesitate in your duty.'

"'My duty?' he said. 'Oh yes, of course; my duty. You mean, of course,
that any law-abiding citizen who knows of evidence should bring it out.
Just so. Of course _I_ haven't any evidence--that paper gave me the
first news of the thing.'

"'I think,' I rejoined, 'that anybody who was possessed of even less
than evidence--of any suspicion which might lead to evidence--should go
at once and place the authorities in possession of all he knows or
suspects.'

"'Yes,' he said--very calmly now, though it seemed at cost of a great
effort--'so he should; so he should, no doubt, in any ordinary case. But
sometimes there are difficulties, you know--great difficulties.' He
stopped and looked at me furtively and uneasily. 'A man might fear for
his own safety--he might even know that to say what he knew would be to
condemn himself to sudden death; and more, perhaps, more. Suppose--it
might be, you know--suppose, for instance, a man was placed between the
alternatives of neglecting this duty and of breaking a--well an oath, a
binding oath of a very serious--terrible--character? An oath, we will
say, made previou