which is the same thing.’

‘How?’ inquired the doctor.

‘Thus. It is quite clear that we shall have extreme difficulty in getting to the bottom of this mystery, unless we can bring this man, Monks, upon his knees. That can only be done by stratagem, and by catching him when he is not surrounded by these people. For, suppose he were apprehended, we have no proof against him. He is not even (so far as we know, or as the facts appear to us) concerned with the gang in any of their robberies. If he were not discharged, it is very unlikely that he could receive any further punishment than being committed to prison as a rogue and vagabond; and of course ever afterwards his mouth would be so obstinately closed that he might as well, for our purposes, be deaf, dumb, blind, and an idiot.’