Knox was engaged in a theological discussion with scientist John Scott Haldane. 'In a universe containing millions of planets,' reasoned Haldane, 'is it not inevitable that life should appear on at least one of them?' 'Sir,' replied Knox, 'if Scotland Yard found a body in your cabin trunk, would you tell them: 'There are millions of trunks in the world; surely one of them must contain a body? I think the would still want to know who put it there'.