188 ESSAY ON THE RATIONALE OF 



more hypotheses than one, the true cause is manifestly not discovered. 

 This is the master principle which governs every other principle, 

 and every case of circumstantial evidence. In physical science, 

 though the phenomena may be accounted for by more hypotheses 

 than one, no prejudicial consequence follows from the uncertainty. 

 It is known, for instance, that solar light consists of rays of three 

 kinds, calorific, non-calorific, and chemical ; and the constitution of 

 light may be accounted for equally well, by the supposition that it 

 is composed of three distinct principles, or that it consists of distinct 

 rays, having different degrees of refrangibility. 



Nor is it essential, in physical investigation, that any decided 

 conclusion should be formed as to the cause of the phenomena ; 

 whereas, in moral investigation, it essentially constitutes the only 

 subject matter of inquiry, and erroneous conclusions are not merely 

 harmless but fatally dangerous. 



It is a cardinal and admirable maxim in Courts of Justice, where 

 the subject of evidence is seen treated to the greatest advantage, 

 always to require direct proof of the corpus delicti, and of every fact 

 which goes to constitute the corpus delicti. For instance, in case 

 of alleged murder, express proof must be given of the fact of 

 death, before any inquiry can be gone into as to its cause or author. 

 This rule is borrowed by us from the Romans, those great lights in 

 jurisprudence ; and the disregard of it formerly led to convictions 

 and executions of murder, where the alleged victims have after- 

 wards appeared, of which I could recount many singularly interest- 

 ing cases. 



Having thus excluded the possibility of mistake as to the cause of 

 death, tlie next step in the proof of the corpus delicti is to exclude, 

 by the method of exhaustions, as it were, the possible hypotheses of 

 death from self-inflicted violence, accident, or natural cause ; and 

 not until it is clearly established that no other hypothesis will ra- 

 tionally account for the facts can we adopt the remaining one of death 

 from foreign violence. The discrimination of the several causes of 

 death often involves the profoundest considerations of science, and 

 belongs to the department of Medical Jurisprudence. But it apper- 

 tains to that department of the subject of which I have undertaken to 

 treat, to determine whether conviction of murder by poisoning ought 

 ever to be permitted merely upon presumption, and without express 

 proof of the administration of poison, whether by its discovery in 

 the human body or otherwise. Some medical writers lean to the 

 opinion of the sufficiency of this kind of proof, but the opinion of 

 others, and amongst them that of Orfila, and the inclination of the 



