"'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 previously, without any foreknowledge of the crime?' "I said that any such oath taken without foreknowledge of the crime could not have contemplated such an event, and that however wrong the taking of such an oath might have been in itself, to assist in concealing such a crime as this murder was infinitely worse--infinitely worse than taking the oath, and infinitely worse than breaking it. Though as to the latter, I repeated that any such engagement made without contemplation or foreknowledge of such a crime would seem to be void in that respect. I went further--much further. I conjured him to make no secret of anything he might know, and not to burden his conscience with complicity--for that was what concealment would amount to--in such a terrible crime. I added some further exhortations which I need not repeat now, and presently his assumed calmness departed utterly, and he became even more agitated than when first he came. He would say nothing further, however, and in the end he went away, saying he would 'think over the matter very seriously.'